In order to take full advantage of gnome-user-share, you must have
devel/gnomevfs2 built with Howl support.  If you do not, simply rebuild
devel/gnomevfs2 after gnome-user-share is installed:

# portupgrade -f devel/gnomevfs2

Next, start mDNSResponder as root.  You might consider adding an rc.d script
for this:

# mDNSResponder

Finally, run gnome-file-share-properties as the user with which you want
to use gnome-user-share, then logout and log back into GNOME.  Now everything
under ~/Public should be shared.  You can view this by opening Nautilus, and
clicking on the Network icon under Computer.