There's a link to a (very) brief story on the event here.
Based solely on that report, and my knowledge of dolphins, I have to say that I don't buy the "freak accident" angle. I would speculate that two animals, in different parts of the pool, were cued to do this jump within seconds of each other.
If one dolphin is in the water, and the other's already out of it on an aerial behavior, they'll both lose the normally-keen sense they'd have of each other's location. Given that, I think it's very possible (though rare) that such a collision could occur in a captive environment, but I would tend to believe that the fault would lie far more with the training staff than with the animals. This is certainly the first I've ever heard of such a thing.
I suspect that the trainer responsible was not keeping an eye on what their colleagues were doing. If this is indeed what happened, I feel sorry for them both, and I would hope that Sea World institutes any changes necessary to prevent something like this happening again.
I would still like to hear clear details of what happened.
Sharky was performing a jump for park visitors when she collided with the other mammal and died, said spokeswoman Becca Bides. Visitors who witnessed the accident were standing more than 50 feet away, Bides said.
This was the first time dolphins fatally collided at the park, Bide said. "Even though it's rare, we're taking this very seriously."
Bides said park officials will examine training protocols and the dolphins' aerial behaviors and routes.----------------------------------------As more news is reported I will add it to the comments.The following comment was from News Redio 580 WDBO
---------------------------------------------A dolphin is dead after a freak accident at Sea World's Discovery Cove.
The 30-year-old dolphin named Sharky was doing her routine aerial tricks when she collided into another dolphin during a live performance. The other dolphin survived, but Sharky did not.
"It's an atmosphere where the dolphins pretty much say what they want to do. If they don't want to do something, its up to them. The trainers don't ever force them. It is all through positive reinforcement."
Sea World's spokesperson says they are launching an investigation to look at training protocols and the park.
Sean Gilligan told Channel 9 that he was visiting the park and witnessed the midair collision. "Just a freak accident. Dolphins have a very good sense of direction. I'm surprised they ran into each other, surprised one died."
The dolphin’s remains will be used for science and research and then will be disposed of according to federal guidelines.