I just received an email the other day from the Project Tango dept. stating that they will be sending out survey to shrink the beta group but allow for them to get to the entire consumer market. There will be a version of project tango for the convention members but it will not be the full beta. That is apparently reserved for those who signed up to play.
there are going to be two different beta groups... The Public Beta group which will get to use a release and the "Private" Beta group which will have a copy that is 3 - 4 weeks more advanced than the public beta