An aspect of Erlang that is often mentioned but seldom highlighted, and fairly unrecognized for its contribution is pattern matching. Languages implementors that wish to achieve Erlang-like concurrency in their own language's runtime will also have to come to terms with Erlang's simple message selection mechanism based on pattern matching.
Again this is where an implementation like Termite, based on Lisp (Scheme) can work as well as Erlang. Other languages not so much, but some creative use of syntax and meta-programming in Smalltalk, Python, and Ruby might do the job.
Other languages not so much. Especially those modern curly braced ones, which will likely have pattern matching piled-on in their next set of features, this time to seem more Erlang-like. Either Java or C# will add this first, then the other language implementors will be compelled to meet or exceed the first.
Either way, they've all got a long way to go. I'd bet on several Lisps and on Smalltalk to keep up most easily.