The functional concept is coming on strong. Note the flurry of activity and interest around Ruby. I've also noticed a bit more interest in JavaScript beyond a mere browser scripting language lately. You can get ahead of the game by diving in now, though the time invested might not pay off this year or next.
It depends on your general game plan. Are you into programming as an end in itself or as a means to an end? If it's the former, go nuts with Haskell. If the latter, stick with mainstream, "employable" languages. Wait for Haskell to take off and then pounce.
