I have gotten a few calls, and IMs today asking what's going on with Activision's Call of Duty 4, and cross-platform play.  Most folks are pointing to a specific IGN interview.

I sent an email to Kevin Unangst, Global Director, Games for Windows, and he replied, saying:

"Given the incredible success of XBOX LIVE on the console – with the Call of Duty franchise a particularly stellar example, I think it’s incredibly premature to dismiss the value of bringing that network and everything it can offer to Windows gamers."