readme.md

Y ejecutas la tarea corriendo lo siguiente en la terminal:

npm run js

Las pruebas las hice con node v6.1.0 y con gulp 3.9.0

gulpfile.js

var gulp = require('gulp'),
    concat = require('gulp-concat'),
    rename = require('gulp-rename'),
    uglify = require('gulp-uglify');

var jsFiles = './componentes/*.js', 
    jsDest = './js/';

gulp.task('scripts', function() { 
    console.log("Running compressing JavaScript task...");
    return gulp.src(jsFiles)
        .pipe(concat('scripts.js'))
        .pipe(gulp.dest(jsDest))
        .pipe(uglify())
        .pipe(rename('scripts.min.js'))
        .pipe(gulp.dest(jsDest));
});

package.json

{
  "name": "gulp-primeros-pasos",
  "version": "0.0.1",
  "description": "Gulp: Primeros pasos",
  "main": "gulpfile.js",
  "author": "jansanchez",
  "license": "MIT",
  "devDependencies": {
    "gulp": "^3.9.0",
    "gulp-concat": "^2.6.0",
    "gulp-rename": "^1.2.2",
    "gulp-uglify": "^1.5.1",
    "jshint": "^2.8.0"
  },
  "repository": {
    "type": "git",
    "url": "https://github.com/jansanchez/gulp-primeros-pasos.git"
  },
  "scripts": {
    "js": "gulp scripts"
  }
}