The Call of Duty 4 Dedicated server files have just been released. Download it here
The linux server files have been updated since this thread was made. You can download the latest updates at icculus.org.
It was ported over to linux by Ryan from icculus.orgPLEASE NOTE:
You'll need to copy the data files from a Windows install. Punkbuster works, but you'll need to run its installer separately (instructions on how to do this from the commandline on your remote server are in the README).
More Info on the linux files here.