RPM of new version 0.49 of the library to communicate with servers is available in remi repository for Fedora et Enterprise Linux. It's also available in rawhide.
As always:
yum --enablerepo=remi install libmemcached
This library is required by the new memcached PECL extension (an alternative to memcache) in active development phase.
As this new version breaks ABI (with previous 0.47), I don't plan any update in the fedora ≤ 15 repository...