Kinda. The KotOR factions (Sith Empire and KotOR-era Galactic Republic) were added as a third era alongside the GCW and Clone Wars stuff, which have remained playable. All of the factions have been rebalanced and new classes were added for each faction, and the KotOR stuff is all unique classes that aren't in the other two eras. Some custom KotOR maps were added, as well as all of the Battlefront I maps, which is pretty grand.
It's pretty neat, really. Well done, save for the KotOR space battles which are all dogfighting and tend to drag on forever.
It's the Star Wars Battlefront II Conversion Pack on ModDB, in case you were wondering.