Check iTunes and see if you have a pending or stalled download in there. If you do, finish that download or delete it if you can. If you can't finish or delete the download on the iPad, do it in iTunes on your computer and then sync the iPad. Then go back to the apps and see if they will download.
If that doesn't work or if that was not the problem, go to Settings>Store >Apple ID, tap your ID and sign out. Then reboot the iPad, Reboot the iPad by holding down on the sleep and home buttons at the same time for about 10-15 seconds until the Apple Logo appears - ignore the red slider - let go of the buttons.
Then go back to Settings>Store>Sign in and sign in again and see if the apps will update.
Hi. This happened to me recently on my iPad2, too. I had apps to update, so I did an "update all". Soon after, all the apps went into a "waiting" state. Couldn't even delete them. Tried a power off/power on reset. Still the same.
After a bunch of searching unsuccessfully for an fix, I started fooling around a bit. Well, my fix was extremely easy. The hard part was find out about it! Well, turns out it's "elegantly simple" just like Apple's intent with most areas of its computing strategy. Cool! Here it is:
Go into the App Store. Now, do this singly for each app in turn. In your list of "waiting" apps, select one by pressing its icon image once.
It will then take you to a larger version of that apps info. Press the icon/image again. Just once.
It will then take you to that particular app on your iPad. Press the icon once. It should start updating.
Do this singly for each app that is waiting to be updated and you list of updates should soon be cleared.
I don't know, possibly a problem with the "update all" code?
Hope this helps you!