Yeah, once it's activated in the settings on both computers, it's really just that easy and it works for game updates as well. Just download it from the server once and then it's copied across Steam Clients on the same subnet. I copied almost 2TB of games between my computers today that I hadn't installed on multiple computers because I didn't want to screw around with waiting for them to download from my slow internet. The instructions and other restrictions are in the link I and Eigenvektor posted.