Rotation lock is not working after upgrade

At the risk of sounding rather snotty. Please read the release notes for iOS 4.2.1 on the iPad or do a search on these forums. This has been discussed not only here but on the internet as a whole to death.

TL:DR Apple changed it in iOS 4 to match the function on other iOS devices. This is NOT a bug. Please read the release notes for iOS 4.2.1

Double click the home button to bring up the multitask bar, slide the bar to the right, you will find an icon with a circular arrow and a lock inside it. press that icon to lock the orientation.

Thanks a ton, I was fussed all day!