As announced, Mac OS 10.6.6 was made available early today, which includes the Mac App Store. You'll find a link to the Store in your Dock once you update.
Grab the OS update now by running Software Update on your Mac. According to Apple, this update lets you:
"Discover Mac apps: Browse featured apps, top charts, and categories, or search for something specific. Read detailed app descriptions and user reviews, and flip through screen shots.
Buy and install: Easily purchase apps with your iTunes account. Apps install in one step and are quickly available from the Dock.
App updates: The Mac App Store keeps track of all your purchased apps and notifies you wh
