If you've been following my tweets, you know that after about 6 months of trying to figure out a new side project, I've decided to teach myself Erlang.
In short, it will have you digging deep in your CS education to remember languages like Prolog and ML. And after using languages like Python, the syntax is, well, ugly. It certainly doesn't read like prose, which many developers love about Rails.
But I think there is some genius in there, and the time is right for rethinking concurrency. I spent a lot of time working on a non-blocking proxy server, and IMHO that model of development isn't going to scale to huge projects, especially in languages like C which have embedded blocking I/O into the brains of developers since day 1.
Prediction: In 10 years all languages will borrow concepts from Erlang. But they may look more like Scala.