Hi,
I'm having this problem and not finding any hints about it on the web.
After JB (iOs 3.2.1) all my regular apps (more than 100) can NOT be upgraded on the iPad. To upgrade I have to upgrade on Mac in iTunes and sync new versions on iPad. Or delete the app and install from scratch.
If I try to upgrade on iPad error message is "Can't connect to server"

Just to make things more complicated, new apps, just bought on the AppStore, CAN be installed regularly, without any issue!!

Any solutions or ideas?
Thanks!!!

this is not a JB issue (I do this all the time on my JB ipad )something else going on.
"Can't connect to server" suggest a communication issue , is the ipad connected via wifi or 3g ?

I would unplug from itunes and make sure you have wifi or 3g connect (test with mail)

Hi LGgeek, thanks for your answer. iPad is working flawlessly since JB. wifi, 3g and eveything is perfect. I'm pretty good with tech since I was a kid on Amiga and I stress my devices with everything I can reach. Yesterday I even installed proswitcher and I'm enjoying multitasking too!
Untill JB, just app updating doesn't work anymore... looks like a mistery, smells like a mistery... it's a mistery!! just jocking, sorry... I'm loosing my hopes, really, it looks like something that happened anly to me with millions of jailbroken ipads out there. I guess that I'll keep this strange issue untill next big update. Ah, the entire message is "Impossible to connect to iTunes Store"... of course just coming from the itunes store where I was looking for updates!!!
If it would happen on my mac, I'd trash some prefs file, but on the ipad what should I do?? Maybe I could to reset the network settings, but I hate loosing wifi passwords and all...