Being Xbox Live certified certainly ads to the value of a game, but the honour is only reserved for the biggest developers or really interesting games.
Smaller developers do not have access to the many features of Xbox Live, in particular achievements and social networking surrounding it.
That is until Fulcrum Mobile Networks Open XLive service. This service, which is currently in open beta, brings most of the features of Xbox Live, including online leader boards, achievements and social networking to smaller developers, and mimics similar systems on iOS.
At the moment it appears to be a free system, but it is not clear how Fulcrum intends to monetize and support the service.
Read more at OpenLive here.