This has been nagging me the past few days. I am not positive it has anything to do with iOS4, but it started then, for me. Basically, I will see there is a new email. I will check it in mail and then after I read/delete/close mail, I will get the audible alert or vibration that there is a new email message. I will then check my mail again, and there is no new message. This happens everyday, multiple times. Anyone else experience/notice this?