It seems the latest version in F11 is 1.5c, but 1.8 is available upstream from some time.
I've updated the active Fedora branches to 1.8d
python-boto-1.8d-1.fc10 has been submitted as an update for Fedora 10. http://admin.fedoraproject.org/updates/python-boto-1.8d-1.fc10
python-boto-1.8d-1.fc11 has been submitted as an update for Fedora 11. http://admin.fedoraproject.org/updates/python-boto-1.8d-1.fc11
python-boto-1.8d-1.fc11 has been pushed to the Fedora 11 stable repository. If problems still persist, please make note of it in this bug report.
python-boto-1.8d-1.fc10 has been pushed to the Fedora 10 stable repository. If problems still persist, please make note of it in this bug report.