We use node.js at alta5. The event-driven, non-blocking I/O model performs well in data-intensive real-time applications like a trading platform.
To be honest the answer will almost certainly be yes for every common programming technology as it just takes one person to use it somewhere to make the answer yes.
Just look at OCaml, before Jane street, most techno logiest on the street had never heard of it and now its very well known.
Probably the canonical answer for this type of question should be this one: http://quant.stackexchange.com/a/304/743
META RANT In general I find these kind of questions a bit troubling for this site for two reasons:
Or put another way, what answer would make the poster happy here?