One of the abiding myths of the industry is that Apple stuff doesn't go wrong. But of course it does, like any other piece of technology things will occasionally fail. However the assumption of perfection has an undesirable side effect: not much in the way of debugging help or even informative messages.
This was brought into sharp relief when I fixed a problem on an iPod Touch this weekend. It had 40 apps sitting saying Waiting... underneath the icon. Nothing would get them to install or allow them to be deleted. Nothing that I could find on the web seemed to address this problem.
I eventually discovered that the issue was that the clock had reset itself to the epoch - 1st January 1970 for those who don't speak UNIX. This wasn't very noticeable, of course, because iPod Touches aren't normally something where you check the time regularly.
Correcting the time unblocked pending updates and lo, all the apps installed themselves properly without any further action. So there you are.