The fares from SFO and LAX to LON have been around this range for a few days... once taxes are added in, the total is around $400 all in. It has been available for sale on travelocity for a few days. There was a brief discussion in another thread:
http://www.flyertalk.com/forum/showthread.php?t=615224
about using a connecting flight on LH as a way to spend a quick day in MUC.