Google Voice is irrelevant to this decision. Schmidt has been recusing himself from all things iPhone related since Anroid. Now he has to recuse himself from all things MacOS related. (I doubt the board discusses Safari and iWork, but they overlap as well) I imagine his presence also constrains the board during general topics. Many relevant asides are foreclosed.

I guess he could stay for laptop and desktop hardware strategy and non-product business issues, but he is increasingly unable to apply the special insight that made him valuable as a board member.

since thats what the press release actually says, I doubt all that many people are going to argue.

It doesn't. There, I told you.

In all probability, it's a case of the google voice debacle being the final straw rather than it being the deciding factor.

His position has been unmaintainable for a while, but it may have made him realise its time to leave.

I think it does have to do with recent events, just not the events you're mentioning.

Having on your board an executive from a company that competes with you in multiple ways is awkward, both for your company and for the executive.