With the launch event for the iPad HD less than two hours away, the online Apple Store is down for U.S. customers. While the store occasionally goes down and then up again, sometimes with no change or only minor changes, the reason this time is pretty clear: they’re preparing for the launch of the iPad.

While there’s been a lot of speculation as to when the iPad HD will be available, this Apple Store outage may provide a clue. Recent reports have said that Apple has already been bringing large quantities of the iPad over from China, where it’s manufactured. The fact that the Apple Store is down before the event even starts, coupled with the fact that Apple already has massive amounts of iPad HDs already sitting on U.S. soil suggests that the iPad HD will be available very soon after today’s launch event.

Apple has been consistently releasing its iOS devices closer and closer to their announcement date – the iPhone 4S was in stores two weeks after the announcement. If the Apple Store is down now, the iPad HD may be available for pre-order as soon as today, and could be in stores very quickly after that. One recent report has suggested that it would hit stores in nine days, on March 16th.

While we won’t know anything for certain until Tim Cook tells us from stage in San Francisco, it’s looking pretty likely that the iPad HD could be in users’ hands very quickly indeed.

Will you preorder an iPad HD? Will you stand in line for one? Let us know in the comments.