Setting up the working xdebug on a virtual guest is the same as setting up the debug for the remote server.
Xdebug in Netbeans for a VirtualBox Guest Host
VirtualBox Update on Fedora 11
New VirtualBox update is available.
VirtualBox on Fedora
Installed an announced VirtualBox version 2.2.2 but could not run it (Fedora 10). This is an updated post, please read on.