It is fresh from the rumour-mill but The Sixth Axis have apparently received some information stating that the critically acclaimed Killzone 2 is going to be getting a sequel sooner rather than later! While we had to wait for years and another console generation to begin before we seen another Killzone game (not taking into account Liberation on the PSP) it looks like we won't have to wait for the next generation to get some more Helghast killing into our lives!
As yet this is not confirmed but i would imagine, given Sony's love of announcing games years before they are released, we will hear about this game soon. This comes fresh off the heels of the developers stating that they have 'taken a back-step' from Killzone 2, could this be to focus on the next game in the million selling franchise?
Link - http://www.thesixthaxis.com/2009/07/30/killzone-3-in-development/