I had the fortune of doing a lot of work with Erlang over the last 3 years, even helping to ship a product that relied on it for some middleware. Erlang is great for some tasks, and if you don't know it (and you're of a programming discipline) you should learn it, if only to get comfortable with Actor concurrency.<p>My newest job requires interoperability with a lot of Java code, so I've been working with Akka, using Scala. While I haven't yet been able to examine if it really can scale the same way that Erlang does, so far its been off to a fairly good start so long as you are disciplined.