Earlier today, Google released an official Gmail App for the iPhone and iPad. Then, without explanation, the app was pulled.
An explanation has now appeared on the Official Gmail Blog site:
Update: 11/2/11: Earlier today we launched a new Gmail app for iOS. Unfortunately, it contained a bug which broke notifications and caused users to see an error message when first opening the app. We’ve removed the app while we correct the problem, and we’re working to bring you a new version soon. Everyone who’s already installed the app can continue to use it.
So, if you have the app, you may not want to use it yet. If you were trying to find it, you can’t get it.