I have a widescreen LCD, so I added a 1680x1050 option - but the screen space is not actually wider, it just ensures that the game gets the right black bars to show at 4:3 within the wider aspect ratio. (I have an ATI card, and the drivers don't auto adjust 4:3 resolutions... grrrr)
I think work on a version that actually fills the widescreen space would come if/when we were doing an XBLA version.