No source. Just look at every new product they release. All of them that started post GWT are based on GWT as far as I can tell. The new AdWords interface be

No source. Just look at every new product they release. All of them that started post GWT are based on GWT as far as I can tell. The new AdWords interface being the latest and Wave coming before that. Even small apps, like their new discovery API browser are GWT based. It makes sense too. They need to support long-run development of large applications. That just becomes much easier given something like GWT and all the associated tooling that comes with it.