After installing/upgrading 'Pidgin protocols plugin for Conversations and Contacts 0.8' for Nokia's N900 Maemo, user cannot login to Facebook.
A restart is required.
Solution suggested by Miaoqing Tan is to killall mission-control in postinst so users can sign in their FB account right after installation.
MC 5.2.7 will come with an mc-reload script that will make MC probe for new protocols. Calling this script in the package's postinst script will fix this bug.
I'm not prepared to kill MC in the postinst, unfortunately, so until then, a reboot is necessary.
Looks like this didn't make it into PR1.2. :-(