Greenlight Beta group: http://steamcommunity.com/groups/greenlightbeta#
What is Steam Greenlight?
Steam Greenlight is a new system that enlists the community's help in picking some of the next games to be released on Steam. Developers post information, screenshots, and videos for their game and seek a critical mass of community support in order to get selected for distribution. Steam Greenlight also helps developers get feedback from potential customers and start creating an active community around their game as early in the development process as they like.
How does this differ from other stores’ submission processes?
The prime difference is the size of the team that gets to decide what gets released. For many stores, there is a team that reviews entries and decides what gets past the gates. We're approaching this from a different angle: The community should be deciding what gets released. After all, it’s the community that will ultimately be the ones deciding which release they spend their money on.
I know of a game that should be here. What do I do?
Go contact the game developer and suggest that they submit their game here for consideration.
What do I need in order to submit my game?
You'll need a valid and non-limited Steam account (yes, that means you'll need to own a game on Steam). Then, you'll need to fill out the submission form, including some information about you and your game. The submission will require:
A square branding image (similar to a box cover) to represent your game in lists and search
At least 1 video showing off your game or presenting your concept
At least 4 screenshots or images
A written description of the game along with tentative system requirements
Do not make fake projects, these will get a you a week ban from the Steam community features, blatant copyright of other games, may be more severe.