Google's Program Manager for Peering and Content Distribution in EMEA did a presentation last month where he outlined some of the challenges of scaling a CDN, talked about how peering fits in and what some of the trends in content delivery are today. The presentation also included some details on Google Global Cache and what different CDN platforms look like. You can download a PDF copy of the presentation here. Updated Feb 3rd: At the request of the presenter, the slides have been removed. While earlier permission was given to post them, since it was a presentation in public, I feel that the person who actually did the presentation overrules that if they don't want it available for download.