I'm putting a lot of time and effort into mastering Scala, because I think that it's the future, paradigmatically speaking. But I think the muddled syntax and the complexity of the language may doom it. But I think it's the vanguard of the revolution. I was really psyched about Pyret (http://www.pyret.org/) when I read about it here over the weekend, and I think it hopefully represents the future of how we program.