If XCOM hit its original release date, the game would be out by now. It was originally set for a March 6, 2012 street date, but was then pushed back to Fiscal Year 2013 (April 1, 2012 through March 31, 2013.)
Now the most current delay in a Take-Two earnings report places the game in Fiscal Year 2014. Meaning the game is now scheduled for sometime between April 1, 2013 through March 31, 2014.
Obviously, that's not exactly a narrow window. We'd be very surprised if XCOM somehow managed to slip beyond 2013. Hopefully we'll get clarification on this issue at E3 in a couple weeks.