Stalker (sorry, GSC, we're done typing it properly) Clear Sky was meant to come out in the US on September 5. Obviously didn't. There was a problem at the printers. But it's OK, they delay isn't a catastrophic one, as the game's now got a release date of September 15. Least, it does for retailers; Steam has it listed as September 15 as well, but publisher Deep Silver is refusing to confirm a simultaneous retail-online release.

S.T.A.L.K.E.R.: Clear Sky Hits US Retail Sept. 15; Steam Release Date Not Yet Determined? [Shacknews]