I have just loaded IOS5 onto an iPad2 (v5 9A334) and apart from not syncing photos, music and videos I can't launch any paid apps.
My iMac has iTunes 10.5 (151) installed which should be the latest.
The icons are visible but when pressed they just revert to the same screen.
If I press the Kindle icon it just displays the same screen back without launching Kindle.
Settings/About shows that I have 130 applications so they are on the iPad.
OK for calendar, Mail, photos etc.
I've tried a hard and soft reset, rebooted but nothing works.

NOTE: Just reloaded everything and it appears to work.
Therefore please ignore this post.