I have discovered an obscurity with my 3G iPhone and MobileMe. Whenever I am connected via 3G or EDGE my mail gets pushed instantaneously to my iPhone. However, if I am connected via Wifi (at home) push to my iPhone mail application doesn't work anymore. I can reproduce this every time. Turn on 3G/EDGE, send myself an email: Works. Switch to WiFi, send myself an email... nothing. Is that weird? Is push not supposed to work via WiFi? What are you guys observing?