Everything is up and running for me in So Cal

Unless Apple themselves has said this, this is actually just a wild guess based on (faulty) magical thinking.  

Lol. Apple rarely say anything.

Did they try to unplug and plug in their gateway router? It's supposed to cure just about any Internet problem.

Sounds like that new billion-dollar data center in North Carolina is really working out well for Apple! Good investment!

I experienced this about 12 hours ago, when trying to purchase a season pass (complete my season).  I tried several times from 2 different MacBooks (both running lion), but only from one network.  I gave up on the season pass and just purchased a couple of individual episodes which worked OK first time.

My analysis:

* it's not a 'simple' error, or network or data centre related - it doesn't affect all transactions equally.

* the error actually does say 'try again later' (or words to that effect).  I personally think *later* can easily mean 24-48 hours.  So until the problem persists for a significant time, Apple's advice in the error message itself is sufficient.

The timing of this problem is annoying because my download giga-mega-kilo-bytes reset on 1st of the month...

Also can not purchase TV shows. It says to try again later. I didn't try to purchase a movie or music recently.

Oops! Someone beat me to it! However I can not buy a single episode and that was about 30 minutes ago.

I had to try to update an app 5 times before it stopped giving the error message and installed, but after that it gave another error message (still updated tho).

No problems for me from either store (iTunes, App). It's probably a geographically localized issue.

I'm in Silicon Valley, for what it's worth.

Interestingly, yesterday was the longest outage for Cox email that I've ever seen, as well.

There's really no excuse for either company. There should not be a single point of failure anywhere in the system.