I'm going to throw another hat into the ring, my boston comrade.
I'm going to say take a look at the iro ss hub. The rear about $40, or the set is $70.
Judging from the quality of the other iro hubs, I'd say that this would be a great deal.
The hubs have large serrated locknuts, and come with real track nuts.
http://irocycle.com/fixedgearandsing...einc/id45.html
Tony @ iro is also a really cool guy.

On the other hand, the surly rear mtb hubs are a proven great ss hub. Just ask any one on the mtbr-ss board about them. I've only heard good things, and I've never heard of a failure of any sort.
I think that what ever optioon that you pic will be a good one, but I would go for the cheaper iro hub. But if I wanted a tried and true hub, the surly would be the way to go.