Doing The Math
Benioff talked about "care, maintenance and white-glove treatment," but he didn't get into a lot of details about the capacity of a Superpod. At last count I think Saleforce had more than 600,000 customers across 15 pods. That's 40,000 per pod, though it's surely the case that one pod might handle 100,000 SMBs where another might handle 5,000 large enterprises.
There was no talk of making fractions of Superpods available and you get the sense that Salesforce really wants to keep this to a selective offering. The more variation you introduce in a data center, the greater the opportunity for mixups and failures. Superpod sounds like the simplest option Salesforce.com could come up with to accommodate dedicated instances.