https://connect.microsoft.com/feedback/ViewFeedback.aspx?FeedbackID=369637&SiteID=226
While this suggestion may not be applicable for standard published games, it is something that might be an issue for community games.
The idea is that when you call NetworkSession.BeginFind you only are returned NetworkSessions in Lobby state. If there are no gamers in lobby state but there are plenty in Playing state this could give the impression to the gamer that no one is playing this specific game online and discourage them from trying again...perhaps giving certain game's online communities a premature death.
I have no metrics or studies to back this claim up so this might not be the case.
But, I don't think it would hurt to much if NetworkSession.EndFind returned a count of the number of players in Playing or Ended state so we could display to our users that people are playing the game and the game's online community is not dead.
Knowing my luck, Shawn will show up in a few minutes and say this functionality is already there. :)