Can’t get Gulp to run: cannot find module ‘gulp-util’

UPDATE

From later versions, there is no need to manually install gulp-util.

Check the new getting started page.

If you still hit this problem try reinstalling your project’s local packages:

rm -rf node_modules/
npm install

OUTDATED ANSWER

You also need to install gulp-util:

 npm install gulp-util --save-dev

From gulp docs- getting started (3.5):

Install gulp and gulp-util in your project devDependencies