Sources confirm that Twitter’s official Mac desktop app will be coming to the Mac App Store by tomorrow — which is also the Mac App Store’s official launch date.

RazorianFly reports it has received a mysterious, vague leak to the effect that the Twitter for Mac app will be launching tomorrow. A few features reported so far are native retweet support, real-time updates and drag-and-drop tweeting capabilities.

Tweetie maker Atebits was acquired by Twitter in the spring of 2010.

In a move that might spell trouble for some third-party Twitterdesktop clients, the app will simply be called “Twitter for Mac,” not “Tweetie 2.0″ or anything like that. Twitter’s name on an official app generally spells an uptick in adoption for the official app, never good news for third-party, single-service app makers.

Stay tuned for a full, hands-on review tomorrow. In the meantime, let us know what you think this will signify for makers of third-party Twitter apps for Mac.