Apple's Online Stores Mysteriously Offline [Updated]

Earlier today, Apple's online stores around the world went down for unknown reasons. Mysteriously, the stores seems to be mostly unreachable, with users only occasionally able to load the pages at all. When store pages do load, they show Apple's usual "We'll be back soon" sticky note, but it is unclear why even that notice can only be reached on a small fraction of attempts.

No specific product updates were expected today, and the store went down a little before 4:30 AM Pacific Time, hours later than Apple's usual window for store updates. And with the store remaining down well beyond the usual time of 5:30 AM Pacific Time when Apple typically brings the store back up after an update, something certainly appears to be seriously wrong.

Speculation on the downtime is naturally running rampant, with observers suggesting everything from a major failure at one of Apple's data centers to a potential denial-of-service attack. Apple has apparently been silent on the issue so far, and thus no official explanation for the outage is known.

Update: Some users have reported success accessing Apple's online stores and seeing them back up with no visible changes. Others are, however, continuing to experience problems connecting to the store.

Update 2: Access to Apple's online stores appears to have essentially returned to normal.