Good answer, and one which cuts to the chase. It's important to keep focus on what the company is actually trying to accomplish with any particular number of programming hours. The silly macho "I've always worked a gazillion hours a week" responses miss the point entirely. I've often worked in environments where people put in 14 hour days and did 2 hours (or in some cases less) worth of productive work. I'd rather have 6 hours of a programmer's undivided focus than 12 hours of internet browsing and sports talk.

For relatively short periods of time it's possible to maintain focus on 10+ hours programming days. My observation, though, is that two things happen after it's gone on for too long. First, the quality of the code plunges as fatigue sets in. Second, while the programmer sits at the monitor for the extended hours, less and less real work is done proportional to the time invested. In general, extended hours should be used only to meet deadlines, and developers should be given a schedule which keeps them rested and able to carry on normal lives outside work.

I'm a high density/diversity sort of person myself, but intuitively the list doesn't surprise me. There are several things going for places like New York and San Francisco. Intelligent young people would tend to gravitate toward places with a lot of stimulation and opportunity. And most of the places near the top of the list still have active economic life. Not many young people stream toward dying agricultural towns, or even non-descript suburban areas.