Ballmer's walking-away-tactic to induce 15% market cap loss which in turn plausibly increases YHOO investors' equivocal sell pressure does sound like a ongoing negotiation to me. Yang meanwhile will have to absorb a lot of shareholders' wrath until the deal goes through to the most eligible of suitors like MSFT.
This is a classic case of "no does not always mean no".

Just a friendly reminder:
there are a lot of numbers between 33.00 and 37.00.