Google (or is it Apple?) somehow never managed to bring us push Gmail on the iPhone, fortunately thanks to push notifications there are now good alternatives to this issue.
Mail notifier is one of them, it's an amazing utility that allows you to receive a push notification every time a new mail reaches your inbox. It's very practical as you get a preview of the messages right away and you can even save some battery by turning off email fetching.
It already allowed you to tap into your Gmail and Hotmail inboxes and with today's update you can now use it with any IMAP-enabled email account.
It goes for $3.99 and it's a must-have.
[Update] : Since September Google actually added the possibility to have traditional push mail, it slipped out of my mind. I nevertheless still believe Mail Notifier is a better solution. Thanks to Dan and Courtney Grey for the tip!