Sony’s confirmed an Uncharted 2 mutliplayer demo for September 15 in a comment on the US PS Blog.
One closed beta took place in June, and a second will begin next Tuesday for anyone who pre-orders the game from GameStop in the US or Play.com in the UK.
The story’s being confused a little by reports of a demo dated September 29. There’s no source for this, though.
We’re checking with Sony.