It's true they are not mutually exclusive. Closure is several related tools that can be used independently: a JS compiler (minifier + type-checker), templates, and very large JS library.

Some people use Angular in place of templates.

http://www.mircozeiss.com/a-radical-new-approach-to-developi... http://google-styleguide.googlecode.com/svn/trunk/angularjs-...

Which ones?

I don't know exactly which groups, but I have been told by an ex-Googler that they are used quite extensively by Google, sometimes in the form of Angular Dart. I have seen some proclaimed stats that they are used by over 120 projects by Google (I believe it was a slide from ng-conf).

I have also seen Angular on some Google pages in the wild, including the older Google Nexus pages.