As we speak, John Barrowman is filming a pilot show in Scotland for the HGTV cable network. If you aren't familiar with it, it's a US channel that shows home makeover shows from dawn 'til dusk.
Actually, it looks like this program will be more a sort of tour of castles and mansions with John acting as host. The little information we do have comes from the John Barrowman Yahoo group. We probably won't know much more about JB's latest endeavor until the show is picked up. They will have to squeeze the show into the schedule somewhere so it's not on opposite one of the other 20 TV programs Barrowman is appearing in.