unknown at this time, but from past SOE titles, they have not used the same client.
everquest for PC and everquest for Mac had different servers -only pc's on pc and only mac on mac (and that is what killed EQmac)
i'd imagine that they would do a same server setup, but shrug...
course i have known about the Agency(not under that name) for a few months- didn't know it was PS3 capable though. If i was going to buy it, i'd buy the PC version Anyway...the software on the Hard Drive will take up probably close to 15% of the space avail for the stock ps3 hd (the 60gig version)...