Valve has updated Steam Greenlight - its crowdsourced distribution decider - to support non-game software and early concepts. Software now has its own section, and works the same as games: community response will be used to judge which programs Valve will distribute on Steam. Concepts are a new feature: they allow developers to bypass the $100 fee to get community feedback on budding game and software ideas, but won't result in Steam distribution.
There are currently only a few software and concept entries. I'm a fan of Eyebot :
He's pretty damn angry. Valve has made a few other changes (mostly developer-oriented; listed below), and they're all live right now.