According to the developers, Final Fantasy X will be as big a change as it was when FF first went from the Super Nintendo to the PlayStation. As the first PlayStation2 FF, it will be released on a single DVD.

Since its annoucement at the same time as Final Fantasy IX, a steady stream of media and information about it has been released by Square. If there's one thing constant about all Final Fantasy games, it's hype. FFX will no longer be using the time-wait ATB battle system present in all previous FFs dating back to Final Fantasy IV. In addition, the characters not present in your party will still be available for use during battles. The skills will also be based around a spherical board, with an "ability level" system for learning new abilities.

FFX takes place in a more Asian-influenced setting, and features a lot of water imagery. The main character, Tidus, plays the underwater sport of blitzball, which will also be featured as a minigame within FFX itself.

The other main character is named Yuna. As per tradition, she is a summoner, and comes from a tribe of such people. There are several other characters, including several people who are her bodyguards to some degree, as she is a member of the "royal family" amongst her tribe. Other characters include Kimahri, Rikku, Auron, Wakka, Lulu, and Braska. Yes, those really are their names. And yes, there will also be a Cid, and an airship. Chocobos are supposedly in the game, as well.

FFX was originally planned to be both a single DVD release, in addition to a two-DVD "enhanced" edition, but the latter was nixed several months ago. Similarly, FFX was also going to feature online access to maps and strategy guides via PlayOnline and the PlayStation2's network adapter, but that was also nixed a while back.

Final Fantasy X will be released in Japan on July 19th, 2001. The North American release is currently slated for February 3rd, 2002. Square has expressed their intention to release FFX in Europe, but no release date has been announced as of yet.

8/22/01: FFX has already sold 2 million copies in Japan, and looks to be far and away the best selling PS2 game so far. Square is still maintaining the tentative February 2002 release in North America, and Square Europe has tentatively announced a projected date of "mid 2002" for European release.
04/02/02:: It's out in North America as of a few months ago...writeups below better describe the game than my amending this writeup.