1080p, scaled down from a 4K scan.

EDIT: Sorry for the terseness. Wrote that while watching a movie. The film has been scanned at 4K and downscaled to 1080p so it will be easier to work with. As this is from a professional, theatrical 35mm print and not a low-resolution Laserdisc scan there is more than enough detail to warrant all 1080 lines of resolution. It's not the same level as the negative, but the last page or so of discussion has highlighted why that's not altogether a bad thing.