There's no doubt that the GTA series has quickly become one of the most popular (and most controversial) series in PC gaming history. Unfortunately for PS2 users looking forward to the next release, GTA: Liberty City Stories won't be released on time for the console, with no particular reason mentioned from Rockstar:

Speaking to Eurogamer today, a spokesperson said "it's looking like it'll be released after Table Tennis", Rockstar's first Xbox 360 title, which is due out on May 26th.
With the impending release of Sony's PlayStation 3 as well as the Revolution from Nintendo, it is probably in Rockstars best interest to release it soon, so likely they have a very good reason for the delay. And if it is for QA issues, who wants to play a buggy game? Game delays aren't always a bad thing.