That Call of Duty Elite membership will finally start paying for itself today, as a pair of new Modern Warfare 3 maps are now available to premium members (non-paying members will have to wait). Specifically, Xbox users with a paid subscription to Elite can snag "Liberation" and "Piazza." In order to do so, simply select the "Download Elite Content" from within the in-game store (found in the multiplayer menu). The Elite website notes that both maps must be downloaded or players will encounter an error during matchmaking.
PS3 Elite premium members will receive the DLC at a later date. The PC version, which does not currently feature Call of Duty Elite, will presumably receive the DLC later as well.