Don't expect to find this mode in the game when it ships next year. Why? "It quickly became apparent that while it's fun for about two seconds to drop portals under people and things like that, it quickly just devolves into pure chaos," Wolpaw explained. "It lost a lot of the stuff that was really entertaining about Portal."
Although Valve have given up on competitive Portal-ing, that hasn't stopped the fan community from creating their own games. Team Portress, for example, mixes a Portal Gun into Team Fortress 2 with some hilarious results.