Moving to Fedora Core 5 requires to rebuild all arch specific Fedora Extras packages. Accordingly build dates, this does not seem to have happened for this package. Please rebuild the package as soon as possible. When you did this already, ignore and close this bugreport please. For more information see http://www.fedoraproject.org/wiki/Extras/FC5Status.
I think, this bug report can be closed as there is http://download.fedora. redhat.com/pub/fedora/linux/extras/5/i386/duplicity-0.4.2-1.fc5.i386.rpm available since 21-May-2006.
Adding Michael as he took the ownership of duplicity nearly 4 weeks ago...
CLosing. Duplicity has been rebuilt :)