WARNING:
If you have upgraded to iOS 8.1 DO NOT DO A HARD REBOOT!
My pad was locked for a couple of hours with the white Apple logo on my screen and I couldn't get out. As I have no laptop I would have been forced to rent one or find a geek at BB to connect me to iTunes for a full restore of my pad.
Luckily after some time the logo disappeared and the screen went black then my sleep screen came up; after a couple of slide on attempts my pad came back but it was uber scary as I thought I lost everything!
(Just watch the White Apple; soon as the screen goes black get ready for your sleep screen or tap reset button once to bring it up then slide on home to your pad as you know & remember it!)
I'd suggest until more run into this glitch that you don't do a hard reboot; heck I'm even nervous about just shutting it down for the night!
Good stuff so far on iOS 8.1 CAMERA ROLL IS BACK~Yeah
PS: iOS 8.1 was fully loaded and operating before this happened; I didn't try that reboot midstream and jam everything up.