According to several threads on the Apple Discussions forum (here, here and here), the iPad’s front camera locks up in the FaceTime app when attempting to establish a video call. It’s unknown how widespread the issue is, but it seems to be stemming from a software bug likely to be addressed with the next iOS release. According to users posting on the forum, the problem won’t go away until device is restarted.
Other hiccups are also being reported. One poster details the issue:
Another user is having troubles with the back camera, too:
Apple yesterday updated the $0.99 FaceTime for Mac app with improved performance when FaceTime is taken full screen.