It only supports 720p, so don't be expecting to play it on an SDTV.
Whether the games only supports 720p or not is irrelevant. All PS3 games will work with an SD TV regardless of what resolutions it states on the back of the cases. The games will just display in 576i.
That's odd, my PS3 says that the game is not supported, yet other games are downscaled when I play them on an SDTV.