The Mbeki and Obasanjo have been advocating talks (and periodically asserting, incorrectly, that talks are actually taking place) almost since the beginning of the farm invasions in 2000.
They are pushing the idea of a "government of national unity", which is Africa's standard method for co-opting and marginalizing and eventually eliminating a troublesome opposition.
Tsvangirai is not swallowing it. He has only to look to the precedence of Joshua Nkomo to see what will happen.