My reader is overflowing with useful things today. I have recently experienced “waiting” apps while I was trying to update a large number of apps at one time. It is almost like one gets stuck or my Internet connections times out so I am left with screens of “waiting” but none of the affected apps are actually updating.
Here is a quick article that describes the issue and a couple of things to try to get those updates moving again. Hope it helps you, it got me through updating 24 apps finally.