A few days ago, I upgraded my 1st generation iPad to iOS 5.1. After that, every time I tried to update my apps, I would get a "WAITING" status which seemed to go on forever and forever.
I thought at first it was just me until I saw many people on social media complaining about the same thing.
This article gave 2 tips on how to fix the issue:
1. Tap an icon till it says "Paused" then tap it again to see if it starts downloading, or
2. Reboot the device (iPad, iPhone or iPod Touch)
Well, I tried both of those to no avail. However, this is what seems to work, at least for my iPad.
I connected my iPad via the cable to my Macbook and opened iTunes. Before doing anything, I first backed up my iPad using the "Sync" button.
Once the iPad was backed up, I clicked on "Apps" on lefthand side of iTunes screen. It would show on the lower right how many app updates are pending. I clicked on that link to go to the page showing which apps had updates. I clicked on an app, entered my iTunes password, and most of the time it would start downloading.
There were a few times when certain apps still would not download/update/install even using this method so I'd defer it for a day. Usually next time I try, it updates successfully.
Try this method and let me know if it works for you. Good luck!