Rihanna has tapped Justin Timberlake as a producer for her 'Good Girl Gone Bad' follow-up. This isn't the first time the chart-topping artists have collaborated. Timberlake wrote and produced the 'Good Girl Gone Bad' track 'Rehab' for the Barbados beauty, and then appeared alongside Rihanna in the song's music video. Their work in the studio has also begun to fuel rumors that the couple are romantically involved.