I hope they have included the original commentary by Roger Ebert -- I wouldn't necessarily expect him to re-record it just for the director's cut (especially since he can't at the moment), but I feel it would be lame if they left it out.
I can't speak for the DVD release, but having just gotten the Blu-Ray release, it seems to me that it the DVD includes the two original commentaries on the Theatrical Cut of the film, as well as three "expanded" commentaries included with the Director's Cut. This means that each of the commentaries have recycled material from the original commentary as well as new material. The new material on the Proyas and Ebert tracks were recorded specifically for the director's cut, whereas the writer's track is essentially the full version of their commentary that was originally edited into the Production Commentary track on the original DVD. All the commentaries have good stuff on them, though I will admit that the redundancy due to the recycled material gets a little hard to sit through if you're doing one track after another. Hope that helps!
Actually, the Ebert and Proyas commentaries were recorded for the laserdisc release. Those are the same commentaries on the BD disc, so they are over 10 years old. However, some more recent comments have been edited in to them for the Director's Cut.