The Apple Store closed its virtual doors at around 9pm PDT last night, and according to CNET will be back with an update at around 1am PDT. Apple is renowned for the temporary outages before major updates are released to customers.
There's no word on what will be added to the store, but CNET speculates it could have to do with the iPhone ordering system - perhaps including the addition of an actual reservation system.
The outage likely has nothing to do with the anticipated Mac OS X Mavericks release, which is expected to be announced on the 22nd of October, alongside a 5th generation iPad refresh which is expected to house an A7X 64-bit processor, adapted from the A7 in the iPhone 5s, and an improved 8MP camera. We may also see an iPad mini refresh where the 7.9-inch device may finally receive a resolution bump with the addition of a 'retina' display.
In any case, we'll update this article when the store comes back online with whatever new features it brings.
Update: It's back online, but we don't see any new products!