Rumours today point towards December 13th as the day that Apple will unveil the Mac App Store. The rumoured date would put Apple way ahead of its scheduled 90 day release window that gave the company up until the end of January 2011.
According to AppleTell an "inside source" stated that Apple is targeting Monday, December 13th for the release of the Mac App Store on Mac OS X Snow Leopard and that developers had been asked to submit applications in preparation for a launch as soon as December 6th. According to the source Steve Jobs has been pushing for a pre-Christmas launch date.
The Mac App Store on Mac OS X Snow Leopard will require Mac OS X 10.6.6 which only entered the developer testing cycle recently.