Standard scraping libraries like lxml, mechanise and nokogiri don't run javascript code.
You'll need to use something like Selenium or PhantomJS.
There have, on occasion, been people trying to use Selenium on ScraperWiki Classic. I'm not sure how they did it though.
Usually scraping javascript sites is enough of a pain that you're best spending time making absolutely sure there's no other way to get the data you're after (eg: guessing IDs that'll be put in URLs, brute-forcing URLs, sniffing AJAX calls to see if there's a pattern in what's requested)
Zarino Zappia
VP of Product, ScraperWiki
@zarino