It's hard to compare WoW benchmarks since you have to be logged in at the same time and be in the same location facing the same direction to really compare the numbers.
One good GPU benchmark for WoW we created in consultation with WoW Mac programmers is to go to FireTree realm and stand at the totem pole at the entrance to Narache Village, "start zone." I have a Warrior run East to the big tree at the top of the hill and back to the totem pole. That provides a consistent reference for GPU framerates. I use Titan Performance plugin to capture min, max, and average FPS.
When you go to a busy location where there's a RAID going in, it's a mixture of CPU and GPU -- and again -- you must be logged in at the same time standing in the same spot and facing in the same direction to compare two different Macs. That's something us forum members may be able to do cooperatively to get an accurate comparison between various flavors of Mac.
FYI, we at Bare Feats Labs have a 3.06 on order with the 4850. Ordered it on March 9th. As soon as it arrives, we'll run WoW and a whole bunch of other GPU benchmarks to compare it to the iMacs with clock speed but with GeForce 130 GT and GeForce 8800 GS. We'll add a few Mac Pros and slower iMacs to the graphs for perspective.