Words are inadequate

There are others who are going for the X-Prize who are much-more open about what they are doing than Burt Rutan is.

John Carmack, most famous for creating Quake, is working on an X-Prize vehicle as well, with his efforts documented at Armadillo Aerospace. He's also an investor in XCOR Aerospace, a company that designs and sells reusable liquid rocket engines, with aims towards supplying a burgening space tourism industry.

Burt Rutan famously said he wasn't going to work on the X-Prize until the prize was fully funded, which told a lot of people that while he was technically capable and highly skilled, he didn't care about space exploration but was interested in the money and PR. It also means that Rutan probably won't be going back once the prize is won.

Carmack, on the otherhand, modified his design and development program to meet the goals of the X-Prize after it was fully funded -- the X-Prize vehicle is less technologically modest than what he wanted, but faster to build. The X-Prize is now developement stage I, and the original idea is Stage II. If Rutan wins the X-Prize race, Carmack will just shift back to his original plans.

There's also the Experimental Rocket Propulsion Society, an amateur, non-profit venture out in California working on a long-term (10 years so far) goal of inexpensive, reusable, manned space vehicles. Their goal has not been met by anyone to date. According to them, the Shuttle is not reusable because part of the launch vehicle is discarded in flight and the entire ship is refurbished between flights. Think airline operations (between flights, crews load/unload, refuel, and do a safety inspection) not shuttle operations (between flights, the engines are broken down and refurbished, the fuel tank is replaced, the entire skin is inspected, etc). Their program is experimental, in that they fly engines, test out new technologies, etc, using one-change-at-a-time experimental protocols. One of their goals is to fly the first rocket powered by an aerospike engine. To date, all aerospike testing worldwide has been static tests or mounted on planes powered by other engines.