PETA has a link to the suit, "asking a federal court to declare that five wild-caught orcas forced to perform at SeaWorld are being held as slaves in violation of the 13th Amendment to the U.S. Constitution," on its site. It involves some of the orcas that have been discussed here, and appears to have received its impetus from the Morgan case (Ingrid Visser is one of the Friends).
I can already imagine the hostility and mockery that will greet it: it's just another kooky stunt from PETA, rights isn't the appropriate framework in which to discuss the ethical status of animals, it's an offense to humans who've been enslaved to suggest that nonhuman animals are, everyone knows the Constitutional basis doesn't exist, and so on. I fervently hope, though, that people will take some time to read the suit and consider the case within a longer historical framework, and will not dismiss or reject the struggle of and for these orcas because of a dislike of PETA or animal rights arguments. (You can read some of the background by clicking on the "whales" tag below.)
I also hope people will consider the point made by Colbert - that we live in a country in which the argument that nonhuman animals can be "people" who can be enslaved is ridiculed but corporations are granted the legal rights of people: