In moving to the iPhone, I gave up 'Push' e-mail, and I'm eager to get it back. The once every 15 minutes model offered by the iPhone isn't quite fast enough for urgent issues, and despite claims that Yahoo's Mail is "Push" on the iPhone, I just don't see it. Maybe it only works for AT&T users -- not sure. In any case, this guide shows us how to set the iPhone to check every 5 mins instead of every 15 minutes (if you're unshackled, like moi). Enjoy.