Today, Dota 2 has finished the beta phase. It is now free-to-play and will be published soon for Linux, after the Linux test phase ran out.
Unfortunately, there is a limited number of players who are allowed to play. The reason for this is the prevention of a server overload.
Don´t worry: If you have already redeemed an Early Access pass, you can still enjoy Dota 2 without further notice.