Not soon enough
In an October 2008 interview, Valve marketing director Doug Lombardi stated that news or an announcement of Episode Three might be revealed near the end of 2008.[7] It wasn't, but Lombardi had previously stated that "the next time you play as Gordon will be longer than the distance between HL2 to Ep1, and Ep1 to Ep2."[7]
http://en.wikipedia.org/wiki/Half-Life_2:_Episode_Three







