Google Inc. (NASDAQ:GOOG) launched the Gmail app for iOS two weeks ago. However it contained a bug that broke notifications and displayed an error message. Google immediately removed the app from the Apple App Store. Now Google has fixed the bug and notifications are now working again.
The app has multiple account support with mobile specific signatures. Google is also working on improving HTML messages such as pinch-to-zoom. If you already have the Gmail app installed, you will need to uninstall it and install the new version.