Bad luck if you've just got home and are trying to activate your new 3G iPhone. It seems Apple's iTunes Store is having a little technical difficulty.
I just noticed it when trying to restore mine to factory settings (long story), and it's currently in limbo as a result – the 'Accessing iTunes Store' message has just hung.
Judging by a Summize search on 'iTunes', plenty of people are Twittering to say they're experiencing the same problem.
Hopefully it won't last too long, but it's not ideal given the huge number of new iPhones that Apple is hoping to sell today (not to mention the millions of 2G iPhone users who want to upgrade their firmware).
For now, it seems you're unable to activate your new iPhone, meaning that it's a semi-brick capable only of emergency calls (warning: don't call the police screaming about your new iPhone not working, they look down on this sort of thing).