According to a Famitsu interview with game director Tetsuya Nomura, translated by Forever Fantasy, development of Final Fantasy Versus XIII has been put on hold. This is because the entire FF Versus XIII team has been moved over to help complete Final Fantasy XIII - Square's highest priority title.
The translation also reveals that while the programmers and planners are all now working on FFXIII, designers are working on FF Versus XIII illustrations and concept art. The story for FF Versus XIII is also said to be complete.
It was revealed yesterday that Final Fantasy XIII won't be playable at Square Enix's August party, so the next hope is now with TGS in October.