I don't know about Sea World San Diego, but the Orlando show is supposedly in previews. I was at the website earlier and it says the official opening (for us) is May 11. I think I'm going to go over some time next week and check it out perhaps.
A friend was just at Sea World San Diego and said "Believe" is not open yet. It was apparently supposed to open a week or so ago, but they're still working on the stage. I forget when exactly he said it opens, but I think it's later this month.