As of 9am PDT/12pm EDT today, 20% of users are currently unable to make purchases on the iTunes Store. That's according to a bunch of you who are yelling at us, and Apple's System Status page.
iTunes Store - 20% of users are affected. Users are unable to make purchases.
All other stores are services seem to be operating normally, so if you're having trouble, hang tight. Apple should have it up and running in no time. Meanwhile, if you can't buy from iTunes, let us know where you are, how long it's been offline for you, and when it starts working again.