The DOTA 2 blog has been updated with the news that developers are listening to player feedback about wanting to play the game as soon as possible rather than to have devs stick to a lengthy beta and adjustment phase.
According to the post, DOTA 2 team will "get it out there as fast as we can". The dev team will be making adjustments and gradually expanding the beta pool over time. Developers are encouraging potential players to get signed up so as not to miss a minute.
Read the full post on the DOTA 2 blog.