There is a new version of mbuffer available.
Latest version : 20090113 
Version in Fedora : 20080507
Thanks for updating the package.
Any progress on this?
Version 20090215 (latest stable)
This bug appears to have been reported against 'rawhide' during the Fedora 11 development cycle.
Changing version to '11'.
More information and reason for this action is here:
Version 20090628 (latest stable)
mbuffer-20090628-1.fc11 has been submitted as an update for Fedora 11.
mbuffer-20090628-1.fc11 has been pushed to the Fedora 11 testing repository. If problems still persist, please make note of it in this bug report.
If you want to test the update, you can install it with
su -c 'yum --enablerepo=updates-testing update mbuffer'. You can provide feedback for this update here: http://admin.fedoraproject.org/updates/F11/FEDORA-2009-7882
mbuffer-20090628-1.fc11 has been pushed to the Fedora 11 stable repository. If problems still persist, please make note of it in this bug report.