  We report a large spin-up glitch in PSR J1846-0258 which coincided with the
onset of magnetar-like behavior on 2006 May 31. We show that the pulsar
experienced an unusually large glitch recovery, with a recovery fraction of
Q=8.7+/- 2.5, resulting in a net decrease of the pulse frequency. Such a glitch
recovery has never before been observed in a rotation-powered pulsar, however,
similar but smaller glitch over-recovery has been recently reported in the
magnetar AXP 4U~0142+61 and may have occurred in the SGR 1900+14. We also
report a large increase in the timing noise of the source. We discuss the
implications of the unusual timing behavior in PSR J1846-0258 on its status as
the first identified magnetically active rotation-powered pulsar.
