On Saturday, NASA managers bit the bullet and put off the launch of the Dawn spacecraft until sometime in September. By that point they'd already delayed the launch four times, the last of these (targeting July 15th) having come earlier on Saturday. But poor weather hampered preparations at the Kennedy Space Center all last week, and a crucial tracking ship wasn't yet in position in the Atlantic.
So they'll try again in two months, with a window that extends into October. According to NASA's latest announcement, the delay won't affect Dawn's ability to reach Vesta and Ceres as planned. I suppose a couple more months isn't that big a deal, given that the team will wait 8 years after liftoff for the craft to reach Ceres.