Mine

spec file:
...
# {{{ Post/postun scripts
%post -n lib%name -p %post_ldconfig
%post -n libavcodec -p %post_ldconfig
%post -n libpostproc -p %post_ldconfig
%post -n libavformat -p %post_ldconfig
%post -n libswscale -p %post_ldconfig

%postun -n lib%name -p %postun_ldconfig
%postun -n libavcodec -p %post_ldconfig
%postun -n libpostproc -p %post_ldconfig
%postun -n libavformat -p %post_ldconfig
%postun -n libswscale -p %post_ldconfig

# }}}

# {{{ Files
%files
%_bindir/%name
%_man1dir/%name.*
%dir %_libdir/vhook
...

dist-upgrade:
 4: libswscale               ######################################################################################## [ 40%]
/sbin/ldconfig: relative path `1' used to build cache
error: execution of %postun scriptlet from libswscale-0.4.9-alt1.svn9685 failed, exit status 1

thresh@snowwhite ~/projects/quake3 $ rpm --scripts libswscale
postinstall program: /sbin/ldconfig
postuninstall scriptlet (through /sbin/postun_ldconfig):

# }}}

# {{{ Files