From Yahoo News: http://news.yahoo.com/s/livescience/20100309/sc_livescience/ussittingonmotherlodeofraretechcrucialminerals
China supplies most of the rare earth minerals found in technologies such as hybrid cars, wind turbines, computer hard drives and cell phones, but the U.S. has its own largely untapped reserves that could safeguard future tech innovation.
Those reserves include deposits of both "light" and "heavy" rare earths - families of minerals that help make everything from TV displays to magnets in hybrid electric motors. A company called U.S. Rare Earths holds the only known U.S. deposit of heavy rare earths with a concentration worth mining, according to a recent report by the (USGS).
İ had read (long back) that there were numerous potential sources in the US and many more around the world - İ am not sure about this statement of only one mine - that sounds really fishy. The rare earths have not been economical anywhere except China for years as China is willing to dump it's resources on the market at below value in order to get the market and foreign currency. Difficult to understand Chinese economics - seems they work different than elsewhere.
There are many doomers out there from across the spectrum wringing their hands about lithium (plentiful and not all in Bolivia!), rare earths (plenty to go around for years to come). Rare earths are not even really rare but difficult to find in concentrations that allow commercial mining.