Just saw Blackfish, the documentary about orcas kept in captivity. It makes its message convincingly, and leaves you feeling that we ought not to keep these creatures confined. The interviews with the former SeaWorld trainers are particularly effective.
Orca brains are not only larger than ours, but apparently have more highly developed limbic systems -- the part of the brain which governs emotion.
I was struck by how similar orcas are to elephants. Both creatures are huge, and also hugely intelligent. Both live in extended three generation family groups. Both grieve when their offspring die. Even the high pitched sounds they make when distressed sound somewhat similar. Elephants have better memories than we do; it is unclear whether orcas do.
It might prove impossible, but it would seem worth our while to have researchers attempt to follow these creatures in their natural environment and attempt to learn their "language" in some sort of Berlitz-with-the-aid-of-high-tech fashion. There's probably something to be gained.