According to Gamefly they are and the rumor is far from unbelievable. Last month Konami announced Metal Gear Solid: Portable Ops Plus for Japan without corresponding news for the rest of the world. For single players the plus adds in the Infinity Missions and for online play there are some new characters. Since the expansion disc comes out on September 20 in Japan we should get additional details about the new content. In the meantime check out the trailer.
Sometimes we'll publish a story as a group. You'll find collaborative stories and some housekeeping announcements under this mysterious camel.