I am very sorry if your planet has been spammed by my blog. I did an OS upgrade on my server and for some reason the distro maintainers thought it was a good idea to globally enable mod_disk_cache by default.
From the mod_cache documentation:
This module should be used with care and can be used to circumvent
Denydirectives. You should not enable caching for any content to which you wish to limit access by client host name, address or environment variable.
CacheEnable disk /
Wordpress apparently doesn't play well with mod_cache. For me the result was that a request for my feed would return a cached copy of one of my comment feeds. Nice, guys, real nice.