Many, including myself, have noticed that Apple’s iTunes 7.4.1 is causing problems with the iTunes Store. Specifically, people can purchase content, but when attempting to download, are told that “the iTunes Store is temporarily unavailable”. This has been happening for over 24 hours, and is reproduced by running the Check for Purchases… option from the Store menu.
Apple appears to have tacitly admitted that there is an issue, with a basic “we’ll get back to you” email upon contacting iTunes customer service.
What is not clear is how broad this issue is currently. It does not appear to be affecting all iTunes customers, but there does not appear to be any clear difference between users that are affected, and those that are not. Taking a personal guess, it could be corrupted iTunes installs (when iPhone came out, the associated update had similar issues with activation… solved by plugging the iPhone into another machine to activate).
But, hopefully this is a server-side maintenance related to the recent changes on iTunes (improved searching, ringtones, etc). PhoneNews.com is actually suffering a few issues right now that you aren’t even seeing, so believe me, some server-side problems can take more than a day to fix.
Update: Problem appears to be fixed now… people checking for purchases (including myself) are now able to download the content that they have purchased.