The Maximum Attack G event begins this Friday, unlocking the original Phantasy Star Online stages for play in PSU. Sadly, most of the original creatures aren't present, replaced by reskins of PSU models, but the stages all look like they're going to be very faithful to the originals. Some of the more beloved PSO weapons are returning as loot, and as long as the players do at least a half-assed job in the event, the ruins stage will be unlocked in fairly short order.
When the event is done, the stages will remain accessible indefinitely, and the loot will still be out there, but some of the bonus items and experience will no longer apply.
I could care less about the event, but having another opportunity to visit PSO with the much better weapons switching and class mechanics of PSU is golden.