According to a Ukrainian News post, Kiev-based game studio GSC Game World is closing down. CEO Sergei Grigorovich has stated this is for "personal reasons." Sergei is one of the richest men in Ukraine, and many believe the reason for the closing is due to the Mob attempting to extort him, or the corrupt government attempting to claim GSC's assets.
I'm personally disappointed. S.T.A.L.K.E.R was one of my favorite game series. I really hope 4A Games, the developer of the Metro games, picks up the IP. They were founded by former GSC people, so they know how a S.T.A.L.K.E.R game should feel.
Link to translated news article: