I have set up push Gmail on the iPhone 4 through the Exchange Server and that is working great (seems to be faster than with my 3GS). What I'm wondering is if there have already been any good experiences with any of the push notification apps (the ones that create push notifications like we get for SMS). I used PushGmail (http://web.me.com/everything/PushGmail/PushGmail.html) on my 3GS, and it was mostly good. It doesn't work now that I've transferred it over to my iPhone 4. Any experiences? Thanks!