I'm sure this has been done but out of curiosity I wrote a (highly unscientific) little script to count the times that some languages are mentioned herein[1].  The results:
    java: 53
    python: 28
    ruby: 16
    php: 14
    node: 9

Winnah: Java! :)
EDIT: Thank you goo!
Take 2, maybe it will work better:
    java: 42
    python: 38
    javascript: 34
    ruby: 24
    php: 16
    node: 15

[1] <a href="https://gist.github.com/1718350" >https://gist.github.com/1718350</a> [updated for]
Ask HN: Who is Hiring? (February 2012)