There are now reports that Arthur Mutambara, whose party, the MDC-Mutambara, has 7 seats, and thus the margin of majority in the Zimbabwean parliament, may have cut a deal with Mubame, though his representatives are denying this, or claiming that there is a deal, but that it would not take effect unless Morgan Tsvangerai, or at least the MDC-Tsvangerai, was also a part of the agreement.
If this is a sellout by MDC-M of MDC-T, which I see as likely, then we know why Mugabe agreed to talks, because he needed time to stack the deck.