The only real desktop "Startup" in recent times is doubleTwist. Most other are either client for a web service, or more of a lifestyle business than a startup.

The only real desktop "Startup" in recent times is doubleTwist. Most other are either client for a web service, or more of a lifestyle business than a startup. On a sidenote: That doesn't really count either, but MacHeist has done fantastically well selling Mac desktop software in bundles online.