iOS4 actually has great support for gmail finally. You can enable archive instead of delete in the options now (may have to re-add the account). In iOS 4.1 they

iOS4 actually has great support for gmail finally. You can enable archive instead of delete in the options now (may have to re-add the account). In iOS 4.1 they even changed the icon away from the trash can when you have this enabled. That being said, I miss support for priority inbox already.