No idea, though, I am running a 27" BTO iMac with a 3.4GHz quad-core i7, 2GB AMD Radeon HD 6970M, 16GB RAM. I will check the next time I update my system, maybe tomorrow.
I do have to say that my iMac has frozen twice within the last two weeks/since upgrading to Lion. I think the freezing was due to 32-bit Adobe Flash running into a memory wall on a 64-bit machine and OS and caused the entire system to freeze/hang. Hopefully this addresses that issue along with the high temperatures the GPU is suffering under Lion.