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] https://gist.github.com/1718350 [updated for]