Since the iPhone 3.0 Jailbreak has become available, and now with both purplera1n and redsn0w coming on line with iPhone 3GS Jailbreak solutions, we've heard rumblings about problems with Push Notifications not working, or not working properly.
The Dev Team has noted this:
we have some remaining 3.0 jailbreak issues to investigate, including push notification
danmowchan in our forums notes this again today with regards to Prowl. Potential battery drain issues aside, if you've Jailbroken, are you having trouble getting your Push on? If not, has problems with Push made you put your Jailbreak on hold?