Since I am a huge iPhone guy and mobile user, I love when Google and other search engines release mobile search features that are useful. Apps are king on iPhones and Android devices and Google just made them a bit better by letting you easily find apps in Google Mobile Search.
For example, here is a search for a RustyBrick iPhone app that is fairly popular named Hebrew Translator.
And here is a search for Shazam:
Clicking on those links from your iPhone take you to the app store.
Google said , "mobile app search results are available today in the US, with other countries and devices planned for the future."
Forum discussion at WebmasterWorld.