Developer Hi-Rez Studios is currently accepting applications to take part in the upcoming Tribes: Ascend beta, and all you have to do is head on over to this link and input some basic information. If chosen, you will receive an e-mail containing an "Early Testing Program Starter Kit" which explains how to install the game and begin playing.
The beta itself will feature four multiplayer maps, two modes, three vehicles, and twelve playable classes, all of which are set within a 32-player online battle.
So, register, apply, and keep refreshing your inbox! Best of luck to all that apply.