I don't think it is that popular, the largest new serious bicycle supplier in the United States (Trek) has a single road oriented model that is fixed gear (District), and if you include the other suppliers, there might be 2-3 models tops. If it was as popular as some people would have you believe, then every bicycle supplier in the world would be catering to that market with a half dozen models. Fact is, it's no where near as popular amongst the bicycle buying public as some people want us to believe. What is popular in some small circles is to take older road bikes and turn it into a fixed by swapping out the rear wheel, taking off the safety equipment (read brakes) and then butchering it with a hacksaw so it can't be converted back for less then 5 times the value of the frame.