According to Blabbermouth.net there are rumours that Ronnie JamesDio, Tony Iommi, Geezer Butler and Bill Ward will play some major festival shows next summer billed as "Heaven and hell", the name of the classic album they recorded as members of Black Sabbath.
They cannot bill themselves as Black Sabbath for "legal reasons", which I assume is that Ozzy Osbourne probably owns the name in a deal cut before the original bands reunion (way to go, Sharon).
This will probably be in promotion of the "Black Sabbath:The Dio Years" which is soon to be released and contains new Dio/Iommi compositions as well as material from the classics "Heaven and hell", "Mob Rules", "Dehumanizer" and the much maligned "Live eviL".
Source: www.blabbermouth.net