I'm in the same boat with you mrgreaper!
I got a free voucher for Pain when I bought my PS3. So I've had the game for quite some time. I also have a 65" dlp hdtv that's 3D capable.
I set my tv to 3D mode. I loaded up Pain (after downloading the update, and the free 3D packs from the store). When I go into the levels, nothing has changed! The screen looks like it always does. I'm not sure if there's an option we have to select to force it into 3D?
I also downloaded the Super Stardust HD demo, thinking that maybe there would be something in there that would give the option, and nothing.
Has anyone gotten the 3D to work? And if so, was it automatic or did it give an extra option somewhere to use it? It would really suck if you could only use the "latest" tv's for 3D.