I am also peeved about this. (Un?)fortunately, it seems Torchwood has ended anyway, so it looks like we wouldn't have been seeing him again anyway. Although the fact that Jack's hopped it and Gwen's settling down leaves the question of who the hell's gonna monitor the Rift?
Guess Jack didn't think that one through before deciding there was nothing left for him on Earth. What a nerfherder.
Taking a TV programme seriously? Me? No, 'course not.
Links for the uninitiated:TorchwoodChildren of Earth
Edit: Heh, nerfherder. Gotta love the FubTub censors.