Apple has apparently notified developers that it is now accepting submissions for the upcoming Mac App Store. An email to devs from Apple has links on how to set up an iTunes Connect account and the associated certificates. Developers can send apps in right now to have them ready for the approval process for the new Mac App Store. There's no word yet on which developers are jumping on this, but I'm sure we'll find out when the store goes live soon which developers took advantage of this opportunity right away.
And when we say soon, we mean it -- Apple originally said that developers would be able to start submitting apps in November, and, t