Sega has announced that the Xbox 360 servers for Phantasy Star Universe will be closing on 7 September 2012. The reason cited is to have more resources available to prepare for the future and to provide us with "new opportunities and new experiences".
If you still have a GUARDIANS License active when the game shuts down, you will be "refunded by Microsoft on a pro-rated basis.". Whatever that means.
This news comes only a little longer than 2 years after the closure of the PS2 and PC servers for the game.