Ouh, this "tertiary" word was never used in the "Playboy advisor" that I used to learn English.
Anyway, 3 Mb cache and 6.4 Gb/s seems to be a good basis for 4-way scalability, but the nothion that propriatery circuitry is in design to make it scaling further suggests that that's about it.
Opteron is also scaling to 4P with little penalty, using "only" 1 Mb cache. They just need to reduce gate size.
But still, why do I have to pay from 40 to 70 K for that server?