I've seen a patch floating around (in a phoronix article) that makes it work with the open source driver.
Also the article mentions it ships with linux drivers. Hence on that basis I'm thinking fglrx will support it relatively quickly once its packaged. Its just been released in the last few days so I haven't seen any other "i have it working in linux with proprietary drivers" reports.
Haven't put down my money yet anyway so no loss even if it isn't
In any event, main use will be for gaming in XP
as long as it works in linux I'm not fussed if the driver isn't great, as long as its stable and runs compiz.
Though having said that, despite all the ATI is going open source hype, my previous experiences with ATI card in linux is nothing but pain, whereas Nvidia cards work fine even if the driver is proprietary.