#fedora channel on the IRC net irc.freenode.net. Keep in mind that the channel is populated by volunteers wanting to help, but folks knowledgable about a specific topic might not always be available.
relnotes@fedoraproject.org
/usr/share/doc/HTML/fedora-release-notes/. Over time, most of the documentation stored in the /usr/share/doc/HTML/ directory tree have moved out of that tree to application_specific directories.
/usr/share/doc/fedora-release-notes-18.0/.