What we do know about the DLC so far is that it will be a DLC pack that contains levels from Tony Hawk Pro Skater 3. A video of Airport and Los Angeles is making the rounds already, with additional levels expected to follow.
Sources indicate to us that right now there is expected to be one DLC pack for certain, and maybe a second one, depending on how well the first DLC pack sells. Each pack will contain 3 or 4 levels (the number apparently has yet to be decided) and an exclusive move, as well as some additional skaters that will be part of the DLC package. The target price for the DLC package is said to be only $5, which, if true, will help it sell very well.
The release date isn’t known yet, but we would expect it sometime after the PC version is released; which we are now expecting to be soon, since the PS3 version is out.