ReactNativeResolverPlugin (WIP) https://github.com/facebook/react-native/issues/278#issuecomment-87197841

ReactNativeResolverPlugin.js

var path = require('path');

function ReactNativeResolverPlugin(reactNativeRoot) {
  if (!reactNativeRoot) {
    reactNativeRoot = path.resolve(__dirname, 'node_modules/react-native');
  }

  this.reactNativeRoot = reactNativeRoot;
}

function _createAliasMapPromise(reactNativeRoot) {
  var blacklist = require(path.resolve(reactNativeRoot, 'packager/blacklist'));
  var ReactPackager = require(path.resolve(reactNativeRoot, 'packager/react-packager'));
  var reactNativePackage = require(path.resolve(reactNativeRoot, 'package'));

  return ReactPackager.getDependencies({
    assetRoots: [reactNativeRoot],
    blacklistRE: blacklist(false),
    projectRoots: [reactNativeRoot]
  }, reactNativePackage.main)
    .then(function (dependencies) {
      return dependencies.filter(function (dependency) {
        return !dependency.isPolyfill;
      });
    })
    .then(function (dependencies) {
      return dependencies.reduce(function (result, dependency) {
        result[dependency.id] = dependency.path;
        return result;
      }, {});
    });
};

ReactNativeResolverPlugin.prototype.apply = function (resolver) {
  var aliasMapPromise = _createAliasMapPromise(this.reactNativeRoot);

  resolver.plugin('module', function (request, cb) {
    aliasMapPromise.then(function (aliasMap) {
      if (aliasMap[request.request]) {
        return this.doResolve('result', {
          path: request.path,
          request: path.relative(request.path, aliasMap[request.request]),
          file: true,
          resolved: true
        }, cb);
      }
      return cb();
    });
  }.bind(this));
};

module.exports = ReactNativeResolverPlugin;

webpack.config.js

var path = require('path');
var webpack = require('webpack');
var ReactNativeResolverPlugin = require('./ReactNativeResolverPlugin');

module.exports = {
  debug: true,
  devtool: 'source-map',
  entry: {
    'index.ios.bundle': path.join(__dirname, 'index.ios')
  },
  module: {
    loaders: [
      {test: /\.js$/, loader: 'babel?blacklist[]=react', exclude: /node_modules\//},
      {test: /\.js$/, loader: 'jsx?harmony&stripTypes', include: /node_modules\/react-native\//},
      {test: /\.jsx$/, loader: 'imports?react=react-native!babel'},
    ]
  },
  output: {
    filename: '[name]'
  },
  plugins: [
    new webpack.DefinePlugin({
      __DEV__: true
    }),
    new webpack.ResolverPlugin([
      new ReactNativeResolverPlugin()
    ], ['normal', 'loader'])
  ],
  resolve: {
    extensions: [
      '',
      '.js',
      '.jsx'
    ]
  }
};