VideoCardz received confirmation from its sources that AMD is going to launch Polaris as the Radeon R9 470 and R9 480 series in the coming weeks, and that the R9 480 is based on Polaris 10.
AMD will be paperlaunching Polaris on June 1st but it appears the company's add-in board partners are not allowed to show prototypes at Computex as AMD is still very secretive about Polaris:
The lack of concrete information has definitely affected the production of custom Polaris boards. What’s interesting is that AMD has not even allowed its partners to show prototypes at Computex. It means that — at best — we can only expect presentations of new cooling solutions, but nothing that could be called officially named after Radeon 400 series, unless… AMD changes its mind.