Members of the development team at Blizzard have already discussed the possibility of a console version of Diablo III, but it's yet to be fully confirmed. That said, a new job ad found on Gamasutra seems to add fuel to rumours that Blizzard is already working on a console version of the game.
According to the ad, Blizzard is looking for a 'Senior Software Engineer' to be a "key contributor on the Diablo team" and help implement "sophisticated networking systems on consoles". The successful applicant will be able to "[d]esign, implement, and maintain networking related game systems for the console game" and "[i]dentify previously unknown issues and offer solutions".
We obviously won't know for sure until Blizzard officially announces it, but considering the fact Blizzard has been toying with the idea of console development, and considering the team has already mentioned Diablo III being a possibility on consoles, a console port of some kind is looking increasingly likely.