Gamespot have confirmed that there is an Unreal Tournament 2003 bonus pack in the works at the moment, and that its likely that the bonus pack will be free! Its likely to contain something in the region of 5 new levels, and a new (undisclosed) game type. Apparently, the new maps will look somewhat different from those currently in the game, as there will be plenty more textures, static meshes, etc being added.

"When asked if the bonus pack would be out in 2003 or before the holidays, he said the ETA is "as soon as we can get it out!""

More here.