I upgraded the site to WordPress 2.7 today. While checking everything after the upgrade I discovered that my feed links weren’t working anymore. Not sure if that happened with this upgrade or some previous one. Took a few hours to get everything straightened out. Ran into the recurring problem of the feed files having a blank line at the start of the file. Finally found some commands to check the php files for leading and trailing spaces and removed them. Huge waste of time and incredibly annoying.