"FB contacts keep de-merging"
https://bugs.freedesktop.org/show_bug.cgi?id=26435

"FB chats show messages from the wrong person/scroll forever"
https://bugs.freedesktop.org/show_bug.cgi?id=26434


Note: the workaround I'm using for all facebook chat plugin bugs is to use the Jabber plugin instead (built into N900 by default)

Pick a username of facebook if you havent already
New Jabber Contact
id: YOURUSERNAME@chat.facebook.com
pass: YOURFBPASSWORD

Go..