According to (the translated version of) a Ruliweb post about a note in the latest issue of CoroCoro Comic, a DS version of the Nintendo 64 Paper Mario is on the way purple monkey dishwasher. No more information is available than that, but the Ruliweb post says that "More news is expected to appear later." Which is obvious, but, really, if this is true, expect an announcement and official screens within the next couple of weeks.
Oh, and allow us to say it first, because you're already getting your commenting hat on: why isn't this Super Mario RPG? We don't know, and we find the decision to port Paper Mario strange, since it's available on the Virtual Console for ten bucks.