Fedora 15 will reach end of life on 2012-06-26, and no further updates
will be pushed out after that time. Additionally, with the recent
release of Fedora 17, no new packages will be added to the Fedora 15
collection.

Please see http://fedoraproject.org/wiki/DistributionUpgrades for more
information on upgrading from Fedora 15 to a newer release.