I really think many are over estimating what a 45nm ASIC is capable of. It certainly won't do what many are suggesting aka BFL stated numbers.
A 22nm or at a push a 28nm might, but it will massively depend on their design which is far from perfect. All the FPGA's on the market including BFL's still have not reached their ceiling limit, so I don't expect them to be pushing an ASIC to it's limit either.

I don't say this flippantly, my dad (him far more than I) and I, have done a lot of encryption based projects, involving FPGA's and ASIC's. He has always focused on hardware, myself more software based.
ASIC are fantastic chips if you can afford the upstart costs, however FPGA's have advanced to a point that they are fast enough that they are being used as the first choice, instead of ASIC.

The original poster brings up accurate statistics, I'm sure they can make a USB powered ASIC, I've used both FPGA's and ASIC that run on those sort of wattage before, they can do a lot, especially the ASIC, but they can't do a double-SHA-256 as frequently as they say.
I estimate the 2.5 watt (coffee warmer) will likely only do 1000 Mhash/s, A long way off their 3500 Mhash/s Statement.