GNOME VFS is available from the GNOME FTP repository:
ftp://ftp.gnome.org
/pub/GNOME/unstable/sources/gnome-vfs
It is also possible to access the source code through the GNOME anonymous CVS system anoncvs.gnome.org, as explained at the URL
https://developer.gnome.org/tools/cvs.html
The name of the module is gnome-vfs.
The GNOME CVS has a web front-end available at the URL
https://cvs.gnome.org