It is widely known that Google included an element of page load time into the Adwords algorithm over a year ago. As expected, this looks likely to roll out to have wider implications for SEO in 2010.
Google is forever on a mission to deliver the "best" search experience to users. With this in mind, delivering traffic to a page or website that does not perform well (e.g. takes forever to display properly) is not a great experience. Hence, using several different tricks - such as any information it can gather from its varity of tagging tools - it can mark up or down based on site performance.
It is clear that this therefore needs to be at the front of mind (if it wasn't already!) when working in web development in 2010. If Matt Cutts suggests that it could "possibly" play a larger part in the algorithm in 2010 then it probably will. A full Video of Matt Cutts discussing various Google updates is below, but to see the page load comments, skip to around 8 mins 30.