I imagine many MAC owners just do not install new GPUs that often so unless if Apple starts selling these cards in their machines, it seems unlikely... (in my opinion).
However, if you run windows, it appears you can use it nicely. (there is an article about it...):
http://www.barefeats.com/wst10g14.html
If I were you, I would sell that MAC and get a PC (perhaps a bulldozer based one?). It would also be much cheaper and probably faster for the same price. It is often a rocky road when you try to modify what Apple gives you....
Although, I found out a link where they say there were drivers in a beta of OS X...but who knows what is the level of support...
http://news.softpedia.com/news/New-Macs-Using-Tahiti-AMD-Graphics-Discovered-in-OS-X-Lion-Code-23825...