Not sure how many of you have heard but it seems like the S.T.A.L.K.E.R. franchise has come to it's end and will most likely not continue to produce more sequels.
At least that's what we can assume from vague tweets by GSC.
Source #1 (9th Dec, 2011)
Source #2 (Dec 13, 2011)
It would be a shame to not see any more of this game. Despite not being the best game around the games that were released alongside it, S.T.A.L.K.E.R. did however have that certain atmosphere to it.
Source #3 (Jan 12, 2012)