Here's your chance to try out the Call of Duty Elite service first
You might need to set up an account at callofduty.com and hope for the e-mail saying you've been invited. This was how most of us got into the beta for World at War.
The e-mail says you can connect with other people who play CoD, test your skills in tournaments and events that award virtual and real prizes, and access personal stats and strategic info to up your game skills. Basically, it's going to be Halo Waypoint for Call of Duty. I didn't really use Waypoint so I didn't think it was popular enough to copy.
Here's a link to the sign-up page so you might be able to bypass registering completely.