Naughty Dog fans attending PAX EAST will be among the first to find out about a "unique event" from the studio. Naughty Dog revealed via their website that they'll be trying "new and fresh things". For a start, five studios will be joining forces at the event: Guerrilla, Media Molecule, Naughty Dog, Sony Santa Monica, and Sony Xdev (it's at Booth #608, if you're heading to PAX).
As you'd expect, there will be lots of rare promo items at PAX and among them is a The Last of Us graphic novel, American Dreams edition (200 of 1000 will be there).
On the back of said graphic novel is a logo for a "unique event":
"Be sure to check out the back cover for a special logo foreshadowing a unique event regarding the studio. Related to that be sure to visit the Naughty Dog team page on Operation Supply Drop’s 8-bit Salute."
This indicates that the event is likely something to do with the Operation Supply Drop Drive.
Here's some of the other awesome stuff you'll be able to pick up at PAX (or on eBay fat inflated prices):