I originally posted this in the 4850 review thread for comparison but it may have been seen as a thread hijack so I'm posting it in a new thread! Also let it be known that I do not think these results are in any way comparable to gameplay performance, they are here as relative data points.

I just did my own little benchmark to compare my 8800GT to the 4850. My system:
Vista 32-bit
E6300 @ 3150MHz
2GB ram at 450 5-5-5-15

Running Crysis Benchmark as follows on my reference clocked 600/1500/900 8800GT:



And now with the exact same settings but my 8800GT overclocked to 729/1836/993:



Considering the massive cpu advantage Jimmy's system has, I'm not too impressed with the 4850 by itself. However, considering how it is a hair faster than a 9800GTX ( with which I think my overclocked GT is comparable) and the overclocking potential and how most people will be able to easily crossfire them, it seems to be a winner!

Last EDIT:I upped my memory frequency from 993mhz overclock to 1100mhz and it net me an average 34.09 FPS using exact same settings as above.

If I were to upgrade, I think I would upgrade to a 4870, provided that the higher clocks result in a marked increase in performance compared to the 4850.