A selected number of people who have opted-in to receive PlayStation emails on the game’s official site will be sent a code; if you are yet to receive one, don’t worry, as they are rolling the betaout in stages.
“Fans that want to get in but may not get an invite can increase their chances by registering on the official site. Remember, we can’t send you Private Beta keys unless you have opted-in to receive them.”
If you received a beta voucher via Uncharted 3, you will be granted access in early 2012.
EGM’s TAKE: For once, opting-in for newsletters has actually paid off.
Source: Starhawk Official Website