Now this game isn't really an MMO. It is more like an Online RPG (similar to Diablo II) but I thought other might be interested.
Personally I played Phantasy Star Online v1 and v2 on the Dreamcast as well as PSO Ep1+2 on the Gamecube.
Phantasy Star > All. I love the whole Futuristic Animé genre, especially when it has cool scenery like the Phantasy Star ORPG series has
Phantasy Star Universe is planned for Xbox 360, PS2 and PC. It will have two components, an Offline story mode (A real, unique story mode this time, not like PSO) and an Online ORPG mode in which you can create a 6 person team and roll an instance.
General info: http://www.gaming-age.com/news/2006/4/19-40
A slideshow of screens: http://media.putfile.com/PSU-Beta-show-v1
The game has been in development for a while so the graphics may not be comparable to say... "next gen" graphics.
The Phantasy Star series has been around for yonks on the Master system and Megadrive although those were a bit before my time.
I did play PS IV back in the hey day but never managed to get very far.