Noone knows yet until they arrive and someone can benchmark and calibrate a matte ones screen.
Schiller said at the Macworld Expo Keynote that the new Matte screen has exactly the same properties as the old one which could mean it doesnt gain the extra colour gamut. In addition to this there isn't anything about it on Apples site, and finally the screen does look suspiously like the old one.
You could always phone Apple?