id Software/Raven/Activision put together 3 new official multiplayer maps for Quake 4 for the PC. They've dubbed this gift as the Quakemas Map Pack. The maps are named "Railed - q4tourney1," "Tremors- q4ctf7," and "Campgrounds Redux - q4dm9." Click the name for screenshots.

Download (24 MB): techPowerUp! | id Software | FileFront mirror

These descriptions are right from id Software's site:

Railed - q4tourney1
Set in an abandoned, rusting Strogg facility, 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 TDM game modes.

Tremors - q4ctf7
Built within a twisting underground cavern, Tremors demands tactical expertise. Enemies attack from above and below in the enormous, multi-tiered environment, making team-play invaluable. Perfect for large CTF games, the map also supports the Arena CTF mode.

Campgrounds Redux - q4dm9
A revitalization of a QUAKE III Arena classic. Excellent for any number of players, Campgrounds Redux supports Deathmatch, TDM and Tournament modes, where hard-core QUAKE fans can get crazy with this throw-back to one of their old favorites.

And the ReadMe.txt:

QUAKE 4(tm) Quakemas Map Pack README

Last updated 12-16-2005

This Map Pack is compatible with QUAKE 4 1.0, and updates
1.0.4.0 and 1.0.5.0.


This Map Pack consists of the file pak013.pk4 and contains the
following multiplayer maps:

Campgrounds Redux (q4dm9) -
With QUAKE 4's updated technology, Campgrounds Redux now has a fresh
look and feel, revitalizing this QUAKE III(tm) 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.

Railed (q4tourney1) -
Set in an abandoned, rusting Strogg facility, the environment in Railed
produces fast-paced frenetic tournament style action! This new map is
all about close-quarters combat and hair-trigger reflexes as players
hustle through the winding, multi-tiered corridors. Designed especially
for Tournament play, Railed also supports Deathmatch and Team Deathmatch
game modes, and is guaranteed to provide some thrilling fast-action
gameplay.

Tremors (q4ctf7) -
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.


To use the new maps in the map rotation cycle, a new map cycle script
file has been included with the Map Pack, called mapcycle-mp1.scriptcfg.
To use the new map cycle script:
1. On the Multiplayer- Create Server screen, click "Advanced Options"
2. In the "Map cycle script file" field, enter mapcycle-mp1.scriptcfg
3. Click "Close advanced options"
4. Start the server

Alternately, this can be set with the console command:
g_mapCycle mapcycle-mp1.scriptcfg


To uninstall, simply delete the pak013.pk4 file from your
QUAKE 4\q4base directory.