Hey, i ran into trouble with that plugin and upgraded the version to 1.69 but after the rebuild with mock it didn't show up in pidgin as an option. I don't know what was wrong since I just changed the sources and nothing besides that. Perhaps you could find the reason. Hope this is of any help: http://hannes.fedorapeople.org/purple-facebookchat-1.69-1.fc14.src.rpm
I found the same problem than you, but don't get the time to analyze in deep. Maybe in some days.
Investigated a bit... Reported upstream: http://code.google.com/p/pidgin-facebookchat/issues/detail?id=909
purple-facebookchat-1.69-1.fc14 has been submitted as an update for Fedora 14. https://admin.fedoraproject.org/updates/purple-facebookchat-1.69-1.fc14
purple-facebookchat-1.69-1.fc13 has been submitted as an update for Fedora 13. https://admin.fedoraproject.org/updates/purple-facebookchat-1.69-1.fc13
purple-facebookchat-1.69-1.fc13 has been pushed to the Fedora 13 testing repository. If problems still persist, please make note of it in this bug report. If you want to test the update, you can install it with su -c 'yum --enablerepo=updates-testing update purple-facebookchat'. You can provide feedback for this update here: https://admin.fedoraproject.org/updates/purple-facebookchat-1.69-1.fc13
purple-facebookchat-1.69-1.fc14 has been pushed to the Fedora 14 stable repository. If problems still persist, please make note of it in this bug report.
purple-facebookchat-1.69-1.fc13 has been pushed to the Fedora 13 stable repository. If problems still persist, please make note of it in this bug report.