I created a new project using the gulp-angular Yeoman generator with language set to TypeScript. Then ran the Gulp build process and also opened the page in a web browser, w
I had the same problem; it appears typings was stripping the original definition file referencing the "ng" import.
Add this back to your original angular/index.d.ts file:
// Collapse angular into ng
import ng = angular;
Or better yet, place it in a ng.d.ts file so it's not overwritten by typings again.