Warning: Update 4.3.1 can brick your iPad if you update on PC
Just a quick heads-up, guys. If you're using a PC (especially a laptop or netbook) to sync your iPad, be aware that a major error can cause your iPad to completely brick during the 4.3.1 firmware update. Many users - including myself - have reported this problem, which causes the update process to freeze halfway through flashing the firmware and rendering your iPad completely useless.
If this does happen to you, you'll need to restore to factory settings and then restore to a backup. Hold the power and home buttons if you can't get it off of the black screen of death or loading bar.
More details: http://discussions.apple.com/thread.jspa?threadID=2797357&tstart=105