Well, apparently there were two separate instances, which I kind of thought from the beginning, given all the conflicting information I was able to gather.
The first one was that someone slipped and was bleeding, and there was the need for a blood transfusion. The captain came on asking for donors, and the response was so overwhelming that they actually turned people away once they had enough.
The second one was the ice skater who was injured, which apparently was during a show, and not during rehearsal. This injury was during a "headbanger" move (that's actually what it's called), where the male partner picks up the female by the legs and swings her up and down, bringing her head very close to the ice. Those of you that watch figure skating probably know what I'm talking about. Anyway, on the upswing, the male skater lost his footing and dropped his partner. She hit her head and had to leave the ice, and did not return.
Hopefully both of these people will be okay.
2007 - Majesty of the Seas (Bahamas)
2009 - Enchantment of the Seas (Western Caribbean)
2010 - Freedom of the Seas (Western Caribbean)
2013 - Golden Princess (Alaska, roundtrip from Seattle)