Guerrilla Games is apparently working in a follow-up to Killzone. Rumours are, however, that the unnamed follow-up will be coming to the New Generation of PlayStation, test units of which are apparently already with at least on Sony game developer.
According to Edge, "the bulk of Guerrilla's staff is getting on with the next Killzone instalment.
Apparently Killzone 2
and 3's Senior Producer Steven Ter Heide acting as "game director on the current Killzone project".
Edge via Gamerzines