On a fresh install in CiviCRM 4.5, caches must be cleared manually before CiviVolunteer menu is built

After a fresh 4.5.0 install, installing CiviVolunteer and clicking an event's Volunteer tab loads the Manage Events screen instead of the volunteer tab.

I suspect this is because the extension installation process fails to build the menu in xml/Menu/Volunteer.xml. Since it finds nothing for the path civicrm/event/manage/volunteer, it falls back to civicrm/event/manage and displays that instead.

I don't recall this being the case in 4.4; I suspect something changed in 4.5.

As a workaround, users may visit civicrm/clearcache to force the menu to be built, then use CiviVolunteer as usual.