It was so exciting at first to read that Phantasy Star Universe is headed for the PSP. Developers have theorized before that a PSP MMO might be worth trying, and PSU is the perfect candidate because of its small-scale group battles and its pick-up-and-play approach. At first, it looked like this would finally be the big break!
Or not! Sega has announced a Japanese PSU port for the PSP, but its multiplayer features are only ad hoc -- meaning it works over a local wi-fi connection between PSPs, not over the internet. So they've taken PSU, stripped out the "Massively" and "Online" parts of "MMO," and ported it to the PSP.
Bad form, Sega -- bad form. Looks like we'll be waiting a bit longer for an MMO-on-the-go that isn't a cell phone game meant for 'tweens. Maybe NCsoft is PSP MMO fans' only hope.