UPDATE They have launched the official website and have details on how you can get into the beta. Below will be the basics to the requirements:
For us it is all about the community. Are you active in the community? Are you playing CS now? To reward the most active players, this week we are giving Beta access to the top 7000 active players around the world in CS:S and CS 1.6. We are also giving out additional keys to the top 500 players of CS:GO.