The mod_pagespeed service does some of these optimisations (plus others). It's almost certainly applying JS concatenation, and in the end there's not much difference in load time:

http://www.webpagetest.org/result/121024_K0_78b60a17cae988da...

EDIT: Actually, it is applying some concatenation, but it's not concatenating everything: http://www.webpagetest.org/result/121024_35_049258ec5056f5b4...