Just to correct you a little bit. Jailbreaking is not the problem, it's the unlocking. I use a jailbroken phone but do use the ATT&T plan and have no push problems, yet get jailbroken advantages. Jailbreaking doesn't mean you don't use the phone without ATT&T ... unlocking does. ( You need to jailbreak to unlock, but not the other way around )
This has nothing to do with AT&T.
Right, just jailbroken phones. They don't get push messages, so they made up a way to make it work. It seems that this made-up way sometimes identifies your phone incorectly to Apple's servers. Not AOL's fault. Not Apple's fault. Not a problem for non-jailbroken phone.
It's also not a problem for jailbroken phones who are just living without push, which seems to be the best solution for the jailbroken folks.