This looks interesting...I'm keeping an eye on it, but a cautious one, since:
a) I'm a bit of a film-noir(e) fan, and I'm really hoping they handle it properly (especially if they're going to call it L.A. Noire!)
b) Was it just me...or did the graphics look kinda...average? don't get me wrong, I don't think graphics are the be-all and end-all, but since this genre has such specific visual characteristics, and given what graphics engines are capable of these days...
It's only a trailer, though - I look forward to more information as it comes out! =)