I never ever believed the possibility of giving out beta codes to people with most posts or kudos. That's just wishful thinking.
All the betas have essentially the same policy -> PS+ first and then everyone else.
I would say that ND (or maybe Sony?) is quite generous to give out a public beta only a week after the closed one... Killzone 3 had a gap of 3 months, if I remember correctly.
Just another reason that PS+ is a waste of money. There's always another way to get the really awesome stuff that it gets. Considering I would have bought inFAMOUS 2 regardless, I see this as a pleasant little bonus.
I was planning on buying inFamous 2 anyway (it looks awesome and I loved the first one), but I probably would have bought the 3 month PSN plus trial for the early access UC3 beta if it wasn't coming with inFamous 2, lol. Maybe anyways. I would have been SOOOO tempted as it got closer to release.
As far as singleplayer spoilers go, I feel like I've already seen most of what the spoilers would be from the multiplayer trailer anyways - I assume in the singleplayer game, you are riding on trucks to try to catch the plane which ends up crashing in the desert (insted of landing in the airport hanger area). The only other spoiler is the Chateau map which I've also already seen, soo.... Unless they add other maps (doubtful, 2 is fine for a beta) or singleplayer skins to the beta besides Drake, Sully, etc. then I doubt there will be spoilers there. So I'm really excited to try it (before, I was hesitant due to spoilers).
My only problem will be... I will be so torn between playing my brand new game (inFamous 2) and Uncharted 3 multiplayer!