I don't think there will be a compact .45 xd-m. The xd-m line are full size pistols. Recently they introduced the 3.8" length so maybe if you wait a year they will offer the .45 in 3.8" . (but its still a big pistol).
Springfield Armory recently announced the release of the 3.8" barrel on the XDm 45. This model will be a compact model, with the shortened grip, and the extended magazine for the full size grip. They have not annouced the release date at this time. Stay tuned to Springfield-armory.com for more info.