HTML is much easier for Google to index and the HTML to dynamic content ratio is believed to be one of many ranking factors that Google will take into account when deciding where to rank your site in the search engine results pages (SERPS).
So how will this affect me and my website?
Well you know all those lovely key-phrase rich comments via Facebook integration or Disqus on your site or blog? – like this one for example. Assuming crawlers haven’t been blocked from indexing JS at robot level, these can now be read by Google and will, in theory, count toward the thematic content on the page or blog post. This is generally good for SEO.
As Matt Cutts stated in his Tweet – ‘Google is Getting Smarter’. An upshot of this is that it is also getting more ‘social’.