While just a small group now, in the coming weeks we will continue to send out batches of codes as we gradually expand the beta; so keep your eyes open. You just might receive an invitation to join! Keep checking back with the blog for more information around the public beta, starting with early access to PlayStation Plus members.
Source.
PASBR is getting a beta this fall. PSN+ Users will be getting early access. I personally can't wait, and I'm tempted to grab a PSN+ card for this, and a few other discounts. (And free games.) I'm assuming this is for both Vita, and PS3. It doesn't say in the source.