Treyarch’s community manager has posted a new blog that talks about building Call of Duty: World at War’s co-op mode from the ground up. Here’s a snippet:

Finding a Co-Op game will work as you’d expect. On the 360 and PS3, you’ll be able to create private Co-Op games, or find public Co-Op games with anyone else around the world. For PC players, we created Co-Op game lobbies, so when you join a Co-Op server in-game – instead of immediately connecting to a server – you join that server’s lobby. The host will then choose the settings, and start the game.

Make sure to read it all.