So, I'm sure there are tons of reports out there, but I just wanted to post my initial experience with the new 8 core 2.26 Core i7 based Mac Pros.
They are fantastic!
I was concerned about the price jump between just getting some used 8 core 2.8 GHZ penryn based mac pros, but, the new mac pro is everything you've hoped for (not quite, come on apple, give us independent FW800 busses and E-sata and two full size DL-DVI) for R3D processing. a stock 2.26 machine with absolutely no upgrades is processing footage from it's own internal drive back to it's own drive (ie, not optimal conditions, but it works for a quick test) at over 12 fps. Details below
4k 2:1 RC 36 B17 with 1 scratch track of audio
processed at a 1/2 Res normal (so 2k) debayer then scaled to 720p ProRes HQ, timecode and reel name burned in with 2 files being processed at once. Obviously things will speed up some when the new ram arrives and it's hooked to a RAID, but for a stock machine, this is pretty fantastic in my eyes. On the same footage I get around 7fps from a stock 8 core 2.8 ghz for reference. You could buy the 2.66 or 2.93, but depending on how many total machines you're getting, the 2.26 has a much higher performance/dollar for R3D processing than anything else (mac wise).