"SpaceX, the upstart start-up rocket company founded
by famous techwealth kingpin Elon Musk, is to build
and test-fly a "Grasshopper" hover rocket based on
the massive first-stage fuel tank of the company's
Falcon 9 vehicle, capable of carrying ten tonnes of
cargo or seven people into orbit.

As yet SpaceX is not discussing the Grasshopper
publicly, but we learn some interesting details of the
new craft from an environmental impact statement
covering planned test flights filed with the Federal
Aviation Administration (65-page PDF/1.4MB).

According to the filing, the Grasshopper is seen as a
"Reusable Launch Vehicle" (RLV). It will be 106ft tall,
and built around the first-stage fuel tank of the existing
Falcon 9 rocket stack:"

See:

http://www.theregister.co.uk/2011/09...hopper_spacex/