Despite initially being very little more than a Dreamcast port last E3, the Gamecube version of Phantasy Star Online has evolved quite a bit in the last year of development.
Phantasy Star Online: Episode I & II now features new character models, weapons, and a completely revamped look and feel from its Dreamcast predecessor. Many of the new weapons take advantage of more complex geometry, as shown in many of the 6 new pictures. There is no word as to if the Xbox version--which was only on display with original character models and areas--will include the "Episode II" aspect of the Gamecube one.
Phantasy Star Online: Episode I & II is currently set for a July release in Japan, with an October 15 debut stateside.