they added a short bonus campaing for single player that was formaly on a demo disc that got lost to times.
they added 4 new multiplayer maps
they fixed graphic bugs and added widescreen support
they dramatically improved controler support
There are fixes with the graphics, new maps and there are new multiplayer servers being active right now. They also fixed a lot of things to make the game work and feel good on new hardware with new aspect ratios etc.