Which feature would those be? Note:I'm not arguing, but rather curious as to what features those are. I wouldn't mind porting to another language - I'm pretty proficient at both java and python, and don't mind some hacking in C. In any case, my request to view the source was to contribute to the current Java tree for now; porting would have to wait.
Yes, some protocols are already implemented this way in the N900. I belive the avahi/bonjour plugin in particular, is a pidgin plugin, being loaded this way. Multi-person IM sessions are supported on XMPP, but I can't remember if I've ever had one on the N900. File sending is missing from the N900 chat UI. I don't know what you mean by broadcast, but if it means "sending to everyone", there's probably some specific account that you send the message to (ie: everyone@s.whatsapp.com), and it gets re-sent to everyone by the WA server. I'm just guessing though, this will probably be verifiable by sniffing :P