As you may know, Black Sabbath have announced their final shows. There have been mixed reports about Bill Ward's possible appearance at the final shows. Ward was not on the last Black Sabbath album and was not on their last tour. On his Facebook page, Ward posted an extensive explanation about his status with the band. As part of his statement, Ward said:

"With a sad heart, I have to say I will not participate in any musical undertakings until a righting of the wrongs spoken against me has been achieved. I must admit, I have little to no expectations of this happening, but in the order of first things first, I’m looking for an honest accountability of all of Ozzy’s statements that I felt were untrue. I would want Ozzy to amend his opinions and exaggerations. I would want him to be forthcoming about his unrealistic viewpoints. And because I was chastised publicly, I would want him to amend publicly in his words, and not through an Ozzy representative, the nature of the wrongs..."

Following that, Ozzy issued an open letter to Ward, accusing Ward of not telling the truth and stating that the reason Ward was not included in recent Black Sabbath activities was due to his heath.
(Source)