rogerd - 2:37 pm on Jan 21, 2011 (gmt 0)
Whatever the ranking effects of page speed, the effects on user behavior are well established. And, with the visibility that Google is giving page speed, you can be sure that sites other than yours will be getting faster.
I'd say forget ranking effects, but work on fast-loading pages purely from a user standpoint. On multiple sites, I've implemented more server power, server-side and browser side caching, and a CDN for stuff like images and script files.