I have a few gulpfiles. One manages my theme in multiple apps and the other manages the app's unique stuff.

gulpfile.js

// Keeps my theme synced in multiple apps

var gulp = require('gulp');
var gutil = require('gulp-util');
var compass = require('gulp-compass');
var clean = require('gulp-clean');

/*
|--------------------------------------------------------------------------
| Config
|--------------------------------------------------------------------------
*/

// Global App CSS
var targetCSSDir = '.tmp/styles';

// Standard App CSS Dir
var appCSSDir = '/public/dist/styles';

// All app dirs
var appDirs = ['owner', 'client', 'middle'];

// iFlat SASS
var iflatSassDir = 'assets/iflat/styles';

// REEN SASS
var reenSassDir = 'assets/reen/styles';

/*
|--------------------------------------------------------------------------
| Release Tasks
|--------------------------------------------------------------------------
|
| Run before each commit and is then pushed to staging and production.
|
*/

// What tasks does running gulp trigger?
gulp.task('default', ['css', 'watch']);
gulp.task('release-css', ['css-iflat', 'release-iflat', 'css-reen', 'release-reen']);

/*
|--------------------------------------------------------------------------
| Watch Tasks
|--------------------------------------------------------------------------
*/

// Keep an eye on Sass, Coffee, and PHP files for changes...
gulp.task('watch-iflat', function () {
  gulp.watch(iflatSassDir + '/**/*.scss', ['css-iflat', 'release-iflat']);
});

gulp.task('watch-reen', function () {
  gulp.watch(reenSassDir + '/**/*.scss', ['css-reen', 'release-reen']);
});

/*
|--------------------------------------------------------------------------
| Small Tasks
|--------------------------------------------------------------------------
|
| Small pieces release tasks so you can be specific in your watch tasks.
|
*/

// Compile iFlat SCSS
gulp.task('css-iflat', function () {
  return gulp.src(iflatSassDir + '/iflat.scss')
    .pipe(compass({
      compress: true,
      css: targetCSSDir,
      sass: iflatSassDir
    })).on('error', gutil.log)
    .pipe(gulp.dest(targetCSSDir));
});

// Copy iFlat styles to each app
gulp.task('release-iflat', function () {
  for (var dir in appDirs) {
    gutil.log("Copying '" + targetCSSDir + "/iflat.css' to '" + appDirs[dir] + appCSSDir + "/iflat.css'");
    gulp.src(targetCSSDir + '/iflat.css')
      .pipe(clean())
      .pipe(gulp.dest(appDirs[dir] + appCSSDir));
  }
});

// Compile REEN SCSS
gulp.task('css-reen', function () {
  return gulp.src(reenSassDir + '/reen.scss')
    .pipe(compass({
      compress: true,
      css: targetCSSDir,
      sass: reenSassDir
    })).on('error', gutil.log)
    .pipe(gulp.dest(targetCSSDir));
});

// Copy REEN styles to each app
gulp.task('release-reen', function () {
  for (var dir in appDirs) {
    gutil.log("Copying '" + targetCSSDir + "/reen.css' to '" + appDirs[dir] + appCSSDir + "/reen.css'");
    gulp.src(targetCSSDir + '/reen.css')
      .pipe(clean())
      .pipe(gulp.dest(appDirs[dir] + appCSSDir));
  }
});

owner-gulpfile.js

// From one of the apps that has it's theme managed by the other gulpfile.js

var gulp = require('gulp');
var gutil = require('gulp-util');
var clean = require('gulp-clean');
var coffee = require('gulp-coffee');
var concat = require('gulp-concat');

/*
|--------------------------------------------------------------------------
| Config
|--------------------------------------------------------------------------
*/

// Coffee and SCSS files
var assetsDir = 'app/assets';

// Temporary dir before concating
var tempDir = '.tmp';

//  HTML files and concatenated and minified JS
var distDir = 'public/dist';

// bower_components
var bowerDir = 'public/bower_components';

/*
|--------------------------------------------------------------------------
| Release Tasks
|--------------------------------------------------------------------------
|
| Run before each commit and is then pushed to staging and production.
|
*/

// TODO Add phpunit
// TODO Add karma + protractor
// TODO Create a 'release' task that runs everything including tests
gulp.task('release-owner', [
  'release-owner-clean',
  'release-owner-copy-views',
  'release-owner-coffee',
  'release-owner-concat'
]);

gulp.task('release-owner-vendor', [
  'release-owner-vendor-clean',
  'release-owner-vendor-concat'
]);

/*
|--------------------------------------------------------------------------
| Watch Tasks
|--------------------------------------------------------------------------
*/

gulp.task('watch-release-owner', function() {
  gulp.watch(assetsDir + '/**/*.html', ['release-owner-copy-views']);
  gulp.watch(assetsDir + '/**/*.coffee', ['release-owner-clean', 'release-owner-coffee', 'release-owner-concat']);
});

/*
|--------------------------------------------------------------------------
| Small Tasks
|--------------------------------------------------------------------------
|
| Small pieces release tasks so you can be specific in your watch tasks.
|
*/

gulp.task('release-owner-clean', function() {
  // Delete old app files
  return gulp.src([
      assetsDir + '/owner/**/[!ownerVendor]*.js',
      tempDir + '/owner/**/*.js'
    ])
    .pipe(clean());
});

gulp.task('release-owner-copy-views', function() {
  // Copy views to dist
  return gulp.src(assetsDir + '/owner/**/*.html')
    .pipe(gulp.dest(distDir + '/owner'));
});

// Compile coffee to js
gulp.task('release-owner-coffee', function() {
  return gulp.src(assetsDir + '/owner/**/*.coffee')
    .pipe(coffee({bare: true}).on('error', gutil.log))
    .pipe(gulp.dest(tempDir + '/owner'));
});

// Concat js and copy to dist
gulp.task('release-owner-concat', function() {
  return gulp.src(tempDir + '/owner/**/*.js')
    .pipe(concat('owner.js'))
    .pipe(gulp.dest(distDir + '/owner'));
});

// Delete old vendor file
gulp.task('release-owner-vendor-clean', function() {
  return gulp.src('public/dist/owner/ownerVendor.js')
    .pipe(clean());
});

// Concat owner vendor files
// TODO make this array smaller or located in package.json
gulp.task('release-owner-vendor-concat', function() {
  gulp.src([
    bowerDir + '/lodash/dist/lodash.min.js',
    bowerDir + '/momentjs/min/moment.min.js',
    bowerDir + '/jquery/dist/jquery.min.js',
    bowerDir + '/bootstrap/dist/js/bootstrap.min.js',
    bowerDir + '/angular/angular.min.js',
    bowerDir + '/angular-animate/angular-animate.min.js',
    bowerDir + '/angular-bootstrap/ui-bootstrap-tpls.min.js',
    bowerDir + '/angular-ui-router/release/angular-ui-router.min.js',
    bowerDir + '/angular-loading-bar/build/loading-bar.min.js',
    bowerDir + '/angular-ui-calendar/src/calendar.js',
    bowerDir + '/jquery-spinner/dist/jquery.spinner.min.js',
    bowerDir + '/seiyria-bootstrap-slider/dist/bootstrap-slider.min.js',
    bowerDir + '/jquery-steps/build/jquery.steps.min.js',
    bowerDir + '/toastr/toastr.min.js',
    bowerDir + '/bootstrap-file-input/bootstrap.file-input.js',
    bowerDir + '/jquery.slimscroll/jquery.slimscroll.min.js',
    bowerDir + '/holderjs/holder.js',
    bowerDir + '/raphael/raphael-min.js',
    bowerDir + '/morris.js/morris.js',
    bowerDir + '/scripts/vendors/responsive-tables.js',
    bowerDir + '/scripts/vendors/jquery.sparkline.min.js',
    bowerDir + '/flot/jquery.flot.js',
    bowerDir + '/flot/jquery.flot.resize.js',
    bowerDir + '/flot/jquery.flot.pie.js',
    bowerDir + '/flot/jquery.flot.stack.js',
    bowerDir + '/flot/jquery.flot.time.js',
    bowerDir + '/gauge.js/dist/gauge.min.js',
    bowerDir + '/jquery.easy-pie-chart/dist/angular.easypiechart.min.js',
    bowerDir + '/angular-wizard/dist/angular-wizard.min.js',
    bowerDir + '/fullcalendar/fullcalendar.min.js',
    bowerDir + '/fullcalendar/gcal.js',
    bowerDir + '/angularjs-imageupload-directive/public/javascripts/imageupload.js',
    '../../clouddueling/public/modules/time/time.js'
  ])
  .pipe(concat('ownerVendor.js'))
  .pipe(gulp.dest('./public/dist/owner'));
});