Here's an article talking about the bump in interest in high speed rail in the US. Atrios mentions that Spain is building a line that will travel the 375 miles from Barcelona to Madrid in 2 and a half hours. Here in SB we have a train to Chicago that's not high speed by any stretch of the imagination, but it's a lot easier and cheaper than flying or driving.
Considering that not even putting an oilman in the White House has kept gas prices from skyrocketing (and in fact made them even less stable), that most of the nation's big cities have WAY too many cars for the size/number of roads and thus have traffic jams all the time, and that airline travel becomes less pleasant every day (3 oz. bottles? Are you f**king kidding me?), I imagine that these trains could really gain traction here if they're given a chance. A train traveling at the same average speed as the Barcelona-Madrid one above could make the trip from:
New York City to Boston in 1 hour and 26 minutes
New York City to Washington, DC in 1 hour and 31 minutes
Los Angeles to San Francisco in 2 hours and 32 minutes
Los Angeles to San Diego in 48 minutes
Dallas to Austin in 1 hour and 18 minutes
Dallas to Houston in 1 hour and 35 minutes
Atlanta to Charlotte in 1 hour and 38 minutes
Atlanta to Memphis in 2 hours and 35 minutes
Miami to Orlando in 1 hour and 36 minutes
Chicago to Detroit in 1 hour and 53 minutes
Chicago to Minneapolis in 2 hours and 43 minutes
You think there might be a clientèle for a train that could do that? Even if it took 50% longer, you think people still might be willing to hop a train that could go from Chi-town to Detroit in 2.5 hours?