Update: The store has gone live earlier than predicted.
Original story: The new App Store for Mac will launch today at 5pm GMT, according to a report.
Apple has only said that the App Store will launch on 6th January and has not officially nailed down a time.
However, The Loop claims to have sources that have pinned it down to the above time, which would make sense, since 5pm is 9am (PT) in Apple's hometown of Cupertino.
The App Store for Mac works a lot like the existing App Store for iOS devices – you can browse by type of app (e.g. games), search for specific items and read user reviews. As with iTunes, the Mac App Store takes control of the installation process too, and helps keep them up to date by alerting you to updates.
Apps purchased on the store should work on all the Macs you own.