Yeah I'm having the same problem as a few people where I'm just not getting any push notifications. I've tried it for AIM only... made sure my session stayed alive for at least 20 minutes. Also turned off/on notifications, rebooted. Still no good. Do I have to be on an at&t network? I have no sim card installed (since I'm still waiting for an unlock) and my phone's jailbroken.
Any feedback's appreciated... thanks.
Mine is pushing over Wifi and 3G. Doesn't seem to matter how you're connected.