The general online consensus is that installing Snow Leopard an a 2011 Mini is NOT possible. The problem is apparently the 2011 Mini's new chip expectations of a fully 64-bit compliant system environment, the loss of necessary drivers that are part of Lion (for example, for the 2011 Mini's graphics processing and/or the Radeon GPU) that don't exist in Snow Leopard or in previous Minis, and other little sabotages that are improvements.
However, one Apple support rep said that he "heard" that it is possible — with perhaps some loss of functionality, but possible. Gotta wait a few days for this one to sort itself out (and I, too, am waiting on proven Snow Leopard compatibility to buy the new Mini!)