We're not sure how many of Google's apps have gotten the iPhone makeover, but GMail (along with Google Calendar before it) look quite optimized for the phone's screen. Of course, there's no real use to optimizing Google Maps for it, so don't expect that one anytime soon. [Google via Boy Genius]
Unfortunately, Google Calendar on iPhone is basically useless. There's no way to view the calendar in any format other than "agenda," and don't even think about trying to see events that are a month or two into the future. I wish they'd just let me log on to standard Google Calendar on iPhone Safari.