It's long been rumored that Urban Justice as a title was canned (including a UK print mag reporting as much in December - something which Vivendi later refuted), but this comment from Vivendi further indicates that there still will be a SWAT 4.
I've documented a lot of the game's rise and fall over at my web site, 10-David (http://www.10-david.com/),
but here's a brief history:
2/2002 - SWAT 4/UJ announced
5/2002 - Shown at E3, but gets ignored by most major media outlets; shaky cam footage shows the game to be in very very very early stages
8/2002 - Last previews published, longtime lead producer Rog Fung announces departure
9/2002 - Rumors of a switch to the Unreal engine crop up
9/2002 - First delays from the original 10/2002 scheduled ship date; pushed into 2003
10/2002 to 1/2003 - Majority of core SWAT 4/UJ staff resigns or leaves company
5/2003 - I go to E3 and hound Sierra/Vivendi for answers; get some, but only leads to more questions
Rest of 2003 - Magazines/retailers/Sierra/Vivendi continue to push date of game back out and Sierra/Vivendi respond to my emails saying something is "coming soon..."
12/2003 - UK print mag says Vivendi told them SWAT UJ was "cancelled" and SWAT 4 was "on hold indefinitely" (name semantics)
2004 - *shrug*