Just wanted to give you guys a heads-up. For those who are sending their iPad 2 for warranty and who was jailbroken before, be careful NOT to restore your backup because apparently the Multi-Gesture is saved (those plist that you guys edited).

I restored mine to 4.3.5 today (need to send in for warranty) and after restoring my backup, found that I can still do multi-gesture. So for those who want to upgrade, be assured that the multi-gesture will not disappear (which is cool) but for those who needs to send it in for warranty claim, make sure you don't restore your backup. Otherwise the service centre will know that it was jailbroken before.