In xsane-0.30-2.i386.rpm , the post-install script contains the line:

ln -s ../../../bin/xsane /usr/lib/gimp/1.0/plug-ins/xsane

which is an attempt to make xsane work as a gimp plugin.  That's great,
except there's one "../" missing, so this line makes a symlink to
/usr/lib/bin/xsane instead of /usr/bin/xsane.  The line should really be:

ln -s ../../../../bin/xsane /usr/lib/gimp/1.0/plug-ins/xsane

Then it will work :-)