I use the 2.2-bleeding SVN build of WP on a local install to test upcoming changes to the system before putting them on my live blog. In order to test accurately, I installed FeedWordPress to pull my live RSS feed. I couldn't figure out why it wouldn't pull my feeds (even after adding all the appropriate snoopy proxy variables in the plugin) unless I set the proxy in wp-includes/class-snoopy.php.