Is there a native Linux application which allows chatting on Facebook Chat? A feature which I particularly require is being able to chat in conversations which include multiple people.
Facebook Chat is based on XMPP. Any XMPP client will work for normal chatting. Group chat is possible with XMPP (specified in XEP-0045) so you will need to look for a client that supports XEP-0045. Pidgin should support this (as there are closed bug reports for fixed history issues relating to Multi-User Chat [MUC]). Empathy and most popular XMPP clients should support this feature though.