One of the known issues with the jailbroken iPhone running iPhone OS 3.0 is that it disables the Push Notification feature. The iPhone Dev Team had released a fix to resolve the issue. However, German developer and founder of Equinux has discovered a major flaw with the Push Notification fix. He discovered that when he sent a message using AOL's AIM iPhone app to a friend in Europe, he received a reply not from his friend, but from a total stranger in the US - a person who had also installed the Push Notification patch. Though it initially seemed to be a problem with AOL's AIM iPhone app, which appeared to be broadcasting instant messages to random, unintended recipients, the issue is due to the Push Notification fix installed on a jailbroken iPhone as it uses the same UDID - Unique Device ID for the fix. Due to this hard-coding, if you send a message to one of a user of a jailbroken iPhone who has installed the push notification fix then other iPhone users who had installed the fix also get the message. It is still not clear if the issue was due to the patch, that the iPhone Dev Team had released or due to the app called Push Fix, that was released by iPhoneIL who had essentially packaged the fix released by the Dev Team and released it on Cydia to make it easier for jailbroken iPhone users. If you have installed the push notification fix then the one of the options would be to restore your iPhone with iPhone OS 3.0 and jailbreak it again.