HandBrake

http://www.barefeats.com/wst10c3.html

They don't give their settings, but we can hopefully assume they used the same on all machines.

Unsurprisingly, a fast 6-core looks like the best deal as a HandBrake/x264 encoding machine. Though a slower 12-core can match its performance while presumably still having some power left for other demanding tasks.

Also, a 2010 quad-core "Nehalem" Xeon appears almost as fast as a 2008 8-core "Core" Xeon with the same clock speed.

The 4 core iMac is right in there with the 8 and 12 core Mac Pros... they're bottlenecking on something single threaded.

Has anyone contacted this guy to determine which version of HB he's using as well as his encode settings?

I haven't. I don't really care; I only posted this as I thought it might be interesting.

But mduell is right; while the smallish difference between the 2008 8-core and the i7 iMac didn't strike me as a huge surprise (the iMac is a Nehalem with HT, Turbo Boost, new memory stuff etc. - plus a slightly higher clock speed), the 6-core 3.33 GHz should probably be faster in comparison to the iMac.