Out today on PSN is a brand new piece of content for Uncharted 3. It's called "Fort Co-Op Adventure" and is a unique departure from the other co-op scenarios available on the Uncharted 3 disc - namely - you play as the villains.
The expansion stars Zoran Lazarevic, Eddy Raja, and Harry Flynn exploring the mystery behind the Janus head statue, which you may remember is one of the relics from another co-op mission from the main game. This content will set you back $5.99, unless you purchased a Fortune Hunter's pass for $24.99, in which it's included. With a total of 14 planned pieces of content - it seems like it might be a really good deal.
The Fort Co-Op Adventure DLC should be out now and supports 3 player online co-op.