One of our members (thanks Bla1ze!) had this to say in the CrackBerry Forums:

Just a note to all those who have/are purchasing a new Blackberry 8310 from AT&T, it may take a little bit longer to get your devices set up, as for some unknown as of yet reason, some of the device PINS are not being recognized by the AT&T database, this is NOT a HUGE problem as it just takes a call to RIM to fix the problem...but also as of now RIM has not sent out emails regarding this issue, but as today is when AT&T has seen the MOST activations of them, I'm sure the issue will be addressed sooner than later.

This was posted in the forums last night. I did some digging and talked to one of my inside AT&T guys this morning who confirmed he saw several devices over the course of yesterday experiencing this exact same issue. Hopefully the problem is already solved!

I figured I would put this in the Blogs to get some feedback from the community - did you pick up an 8310? Was it a flawless or flawed setup?