The Erlang programming language provides an easy-to-use style of concurrent programming. You may never actually use Erlang, but the concepts are transportable to other languages. You might want to read the book Programming Erlang: Software for a Concurrent World .
Fans of functional programming claim that there is no need to learn anything new. Just use a pure functional language, and the compiler or interpreter will automatically parallelize everything. So you might want to learn Haskell, OCaml, or another functional language.