I've been using Julia 0.3 for algorithmic trading in production for about 3 months now, and the language is truly, astoundingly productive. The only thing lacking for me at this point is true multithreading support (so I can fork off a python thread from within julia) - I currently get around this by using a socket interface to pass messages to python.
Edit: For anyone who's interested, an indicative problem is this: http://stackoverflow.com/questions/21113030/async-thread-dea...