[Image: http://i.imgur.com/bNtuwHY.png]
This thing supports the new E5-2600 V3 CPU line, which has up to 18 cores. With two CPUs, that's 36 cores. 72 threads if you want to count HT.
The cost is out of reach for the typical consumer, however. The motherboard alone is meant for professional workstations and costs $600. The pricing for the 16-core CPUs is not yet listed, but a safe guess would be around $3000 ea. I think I'd be satisfied with a 6 + 6 core setup, with each CPU going for around $580.
In all seriousness, I probably won't build this system. Still, I think it's pretty cool that you can buy nice workstation boards at retail now, and they're more feature-packed (i.e. for consumer use) than they used to be.