Hello. I'm getting dead links for both of
"PDF Documentation"
http://sourceforge.net/projects/geoserver/files/GeoServer/2.3.4/geoserver-2.3.4-pdfdoc.zip
"Release Notes"
http://sourceforge.net/projects/geoserver/files/GeoServer/2.3.4/geoserver-2.3.4-release-notes.txt