X3movie.net has an interesting update on when Fox might be targeting X-Men 3...
(11.25) X3's Target Release Month; Year - A short, bit for today, comes from our insider. While major meetings have yet to really pick up on the third X-Men film, 20th Century Fox is currently eyeing these months for 2006: May, June, December...though this is only tentative.
While May is the most safe spot for the studio, they also are considering a possible change, as they might have to deal with these possible films (based only on speculation): the SUPERMAN film (if it gets off ground), and their own upcoming DAREDEVIL sequel, which will be the third film in the DD universe (ELEKTRA being the second). That could very well end up with a 2006 Summer release. And then, there's always SPIDER-MAN 3, which might get rushed out for that Summer also! Tis a crowded year, indeed!
X3 may very well end up being the final film in this specific story-line, as there are no plans for shooting X3/ X4 back-to-back (something the fans have been begging for). The WOLVERINE spin-off film will likely become our X4, with the future of the X-MEN films...or a different mutant ensemble spin-off uncertain. For X3, My money's on May. If it aint broke... Source: Classified