Only things I found by googling were:I suggest using Google. My old iPhone had this problem one time and it wasn't jailbroken. It wouldn't let me download anything. Can't for the life of me remember how I fixed it but Google helped.
If I remember correctly I'm pretty sure it does have something to do with your account.Only things I found by googling were:
Try rebooting the phone
Sign out from the account under settings and then add it again later
SSH into the phone and delete some cache file
Tried all of the above and so far no luck. I think I might have to restore to 5.0.1
Edit: Actually... looks like it might be my iTunes account itself. My laptop is hanging trying to sign in too