I know that at one of the professional lans I went to they actually just burned CD's and labeled them accordingly.
There was a CD case with disks like
COD4
patch 1.0-1.6 installers
For the games they expected people to play they had several copies.
There was also some software they used to have a website hosted on the lan with the tourney sign-ups and brackets and stuff. They had a place where you could post things like "looking for 1 cod4 tourney" and stuff also... I just remember thinking how convenient it was.