Coding has begun on version 2.0 of gravatars. The new codebase will help alleviate a lot of the problems that are cropping up on the current PHP site. It will also incorporate a better business model that will hopefully allow me to run multiple servers and eliminate the resource bottlenecks that are the root of these problems.
Thank you all for your patience, and until 2.0 is out, I will continue to do my best with the tight resources available to me. Thanks again to all the volunteer gravatar raters that free me up to work on making gravatar the best system possible!