Matt: Gravatars aren’t going to hurt your Google rankings
This site’s current design sucks when it comes to showcasing new comments, so in the meanwhile here’s Matt clarifying on a old post about whether Gravatar slows down page load speed and hurt search engine rankings:
…Gravatars (or any images) aren’t going to hurt you in the Google rankings or we would have seen a massive drop-off in traffic on WP.com.
True, because as far as I know page load speed isn’t taken into account yet. And when it is, Gravatars will be just one of the many other factors that influence load speed anyway.