the ICQ Internet message protocol servers recently changed and now require clients to use a newer version of the ICQ protocol. When logging in to ICQ Pidgin 2.5.2 (the version previously shipped with Red Hat Enterprise Linux 5) fails with an error message as a result. Pidgin 2.5.5, included with this update, uses the newer ICQ protocol, which resolves this issue.
Pidgin 2.5.5 also addresses several other minor bugs. Refer to the <ulink type="http" url="http://developer.pidgin.im/wiki/ChangeLog#Version2.5.503012009">Pidgin 2.5.5 ChangeLog</ulink> for details regarding these other changes.