On my own side, I can confirm GoogleBot executes JavaScript, and according to the IP, it was really it, and not just UA spoofing from a browser.
I learned it today, when I wanted to generate some statistics on the use of AdBlockPlus and the likes, when I saw GoogleBot appearing in the logs, which I was not expecting. Seems he also use JavaScript execution to figure some new URLs to crawl; I mean, if a JavaScript loads a page in an IFRAME with some parameters in the URL, it may first try to load the page without the parameters, then only later try to load the page with the parameters. This may suggest it first execute the JavaScript in a kind of sandbox to see what it do.