Next time you get on Call of Duty 3 you will be prompted to complete the update. The COD3 forums state what you can expect from this update. The most significant improvement is that Ranked Matches join lobbies much faster through both Custom and Quick Match. There are also basic HUD and options enhancements.

The one I found most hilarious and useful was the ability to instantly punish medics who intentionally team kill and revive continuously.

Update info

-Hoosierdaddy812-