Google's official App for Gmail has reappeared on the App store. It's (hopefully) less buggy than the last version -- although for Aussie iTunes Store users, it's not that easy to find. Gmail for iOS was meant to be out a couple of weeks ago -- and technically it was -- but you had to be quick, because some game-stopping bugs somehow got past both the boffins at Google and Apple, and the App was hastily pulled from the App store.
It's now back, but at least at the time of writing, it's really badly indexed; if you search the store for "Gmail" you'll find a host of third party gmail alternatives instead. This link should see you through to the official App.