Currently Drupal.org has multiple WebServers that I believe are synchronized to load balance and provide a degree of high availability.
I believe this is done by rsyncing the file directories served by the web. I know there have been criticism of this design on the infrastructure list. I am curious what configurations people are recommending for Apache servers. I am assuming DBs are on separate servers. I am assuming different web servers are used for static pages or cached pages, and for dynamic pages.
Are people using Rsync, NFS mounts, S3?
What has worked best for you and why does it meet your needs?