Gmail Labs has a new feature that extends Gmail's search by showing results from Google Docs and Google Sites. If you enable Apps Search, you'll see a list of results from Google Docs and Google Sites below Gmail's search results. For some reason, Apps Search has a bug and returns incorrect URLs for Google Docs results, but I'm sure this will be fixed.
It's interesting to see that the Gmail Labs feature has been developed by the Apps Search team, which suggests that it's part of a bigger project. Most likely, Google will let you search all your data stored in a Google account from a single search box. If Google's universal search can combine images, videos, books, tweets, news articles in a single search results page, why can't Google develop an unified search service for Gmail messages, Google Calendar events, Google Reader subscriptions, Blogger posts, Picasa Web photos, contacts, tasks, Google Voice history and more?
Tip: If you want to search Google Docs and Google Sites, without displaying Gmail results, add -type:mail to your query.
Unexpected bonus feature: After enabling Apps Search, Gmail will show a "did you mean" message if your query includes misspellings:
