The first person shooter version of XCOM has been delayed until 2013, while the strategy version will be released thrumoured to be due to the fact that moreis year.
Unlike some of the purists out there, I have no problem with the shooter version of XCOM. It is what it is, and combining a shooter with between mission elements such as leveling up characters, building new weapons and picking your next mission could make for a good game. And is does look good.
However, having a turn based version cannot hurt and I am looking forward to that. Not sure why they would delay the FPS version. Each is being made by a different company, so it is not due to moving resources from one game to another. It may be due to the outcry from the purists and some in the media on the FPS version.
XCOM Turn Based Game Information
Three Part Series from Rock, Paper, Shotgun: Part 1, Part 2, Part 3
XCOM FPS on IGN