Assorted navigation service firms say that Google is hard at work developing a mobile navigation app to rival turn-by-turn GPS navigation apps in the App Store. It is suspected that it will be free and ad-supported, and will provide similar turn-by-turn and voice command functionality found in current paid GPS apps.
There have been a few rumblings about Google doing something like this in the past, but that was when the official Maps app was the only app available on iPhones. Now that GPS apps are in the App Store, it is believed that Google's app will take the form of an App Store app as well, rather than being an update to the built-in Maps app.
No known release date is available.
Update: Google has just released the app on their Android platform. We don't know if they will port it to the App Store, but it's a possibility.