This is the new manga by Akira Toriyama. You can the first chapter here.
http://www.vizmanga.com/reader/1140-weekly-shonen-jump-previews-5
There were hints in the first chapter that this takes place in the Dragon World and that has now been confirmed
http://www.kanzenshuu.com/2013/07/16/jaco-the-galactic-patrolmans-tie-in-with-dragon-ball-confirmed/
There is speculation that this is a prequel because one of the hints is that this is going 11 chapters and the first chapter is numbered DB minus 11 and a reference to the reason that Jaco has come to Earth is that an alien threat is on the way. The theory being that threat is baby Goku.
Also Toriyama says this will be his final manga and adds that the reason for the nostalgic look will be a surprise. Which Weekly Shonen Jump promptly spoiled so they could advertise it as new Dragon Ball.