Steam bringing Source Engine mods next week

Valve has announced that they will be hosting popular source engine mods directly on their servers as free downloads (for people who own the respective games the mods are based on) starting next week. 

From the official Steam website:

As a part of our continuing efforts to support the MOD community, we will begin hosting selected MODs directly on Steam starting next week. The first five MODs to ship on steam will be Age of Chivalry, D.I.P.R.I.P., Insurgency, Synergy, and Zombie Panic. As always, owners of any Source game will be able to download and play all of these MODs for free.

Once installed, these MODs will appear in your "My Games" list and will receive automatic updates just like other games on Steam. Also, these MODs now take advantage of Steamworks, which provides stat tracking and tighter integration with the Steam community.

We're excited to see MOD developers get wider recognition for the hard work they have done, and we hope to support more MOD teams in the future. Watch for the official release next week!

Source