'Tis a misleading headline. The story is that Unocal's board merely endorsed Chevron's new bid, much like they did with Chevron's original bid back in April before the ChiComs came a-callin'. It goes to the shareholders for either approval or disapproval on August 10 with the Unocal board's endorcement.
Right you are.
I realized only upon reading the story text that it was only an endorsement by the board and that only shareholders voting will determine acceptance of the offer.
It's so sad, though, that the headline (a declarative statement) was misleading.