Microsoft's HD Photo standard is now officially planned to become JPEG's successor by the Joint Photographic Experts Group, but it'll be known as JPEG XR.
XR stands for extended range, given the wider color palette and finer gradations it can show. Other benefits include in-camera imaging processing support and, supposedly, better compression. Besides losing its Windows-y name (in a former life, it was Windows Media Photo) it's dropping proprietary control by Microsoft to become as neutral as JPEG is now. Though support's already built-in to Windows Vista, it'll take a year to get standardized, at which point large-scale adoption will probably start picking up steam.