id Software & Raven have released the first Quake 4 map pack, adding three new multiplayer maps to the game. Some screenshots can be found here. The descriptions for the maps:

Railed - Set in an abandoned, rusting Strogg facility, the environment in Railed produces fast paced frenetic tournament action. This new map is all about close-quarters combat and hair-trigger reflexes as players hustle through the winding, multi-tiered corridors. Designed particularly for tournament play, Railed also supports Deathmatch and Team Deathmatch game modes, and is guaranteed to provide some thrilling fast-action gameplay.

Tremors - Built within a twisting underground cavern and peppered throughout with pipes, bridges, and catwalks, Tremors demands tactical expertise. Enemies attack from above and below in the enormous, multi-tiered environment, making team-play invaluable. Tremors is perfect for huge Capture-The-Flag games, and also supports the Arena Capture-The-Flag gameplay mode.

Campgrounds Redux - With QUAKE 4's updated technology, Campgrounds Redux now has a fresh look and feel, revitalizing this QUAKE III classic. Excellent for any number of players, this updated version supports Deathmatch, Team Deathmatch and Tournament modes, where hard-core QUAKE fans can get crazy with this throw-back to one of their old favorites.