According to the Thunderer:
The American military is planning a "spaceplane" designed to fly a crack squad of heavily armed marines to trouble spots anywhere in the world within four hours.
At a recent secret meeting at the Pentagon, engineers working on the craft, codenamed Hot Eagle, were told to draw up blueprints for a prototype.
Which would be great, if it was true...
More: http://www.theregister.co.uk/2008/10/20/us_space_marines_times_secret_is_out/
:P