It's the network, the network configuration or the sim cards being given out at some AT&T stores obviously. The iPhones are working fine outside of the US.
Indeed. This is, IMHO, one of the things that will ultimately cause the lawsuit to fail. A suit against AT&T, maybe -- but if it's a carrier-specific issue, Apple's more or less safe.
Another complaint has been filed in Texas relating to this same idea of the 3G connectivity. This time, they complain that Apple is not following their warranty and both Apple and AT&T have misleading advertisement for the iPhone.
Many tests have been run on the 3G and show no evidence of faulty hardware. This time, the plaintiff seems to be aiming more at AT&T.
I have updated my blog post (the same one shown at the beginning of the thread) to explain more about this second lawsuit. It also keeps the information about the 1st complaint: