It is technically possible for H-1Bs to start their own companies, but the barriers to this are very high, and it's still a very rare option. There was a memo released a couple years back that changed the rules: http://www.murthy.com/2012/12/17/entrepreneur-h1b-petitions-...
Interesting, but still rather convoluted and will definitely require costly legal representation.
US could definitely use some sort of medium-length work visa for startups (as opposed to small businesses/traditional companies).
The distinction between startup (or a company in a desirable industry/sector the country wishes to have more of) versus just any business is important to both stimulate growth and also be a selling point to nay-sayers.
