The beta for Uncharted 3: Drake's Deception launched on June 28 for PlayStation Plus subscribers -- or, really, everyone, since anyone who signed up for the Welcome Back program was still inside their complimentary 30 days of PS Plus at that point -- and was originally set to close yesterday, July 13. That's not the case anymore though. The beta now closes tomorrow, July 15, at 9am PDT, Naughty Dog has confirmed.
So go get in there and shoot some bad guys! There are all sorts of bonuses to earn that you'll be able to carry over to the main game. Hell, just starting the beta up nets you an exclusive avatar. What are you waiting for?
Source: Naughty Dog