I think Jabber could do all that you mention. I think the server message logger is called BanderSnatch or JabberWocky (I'm to lazy to check). I think it only logs the XML and doesn't really do anything to it. Some XSLT and a nice search engine could make it accesible to all or a few.
For the bugzilla thing you'll have to do some work, or hire someone to (yes, i'm available atm). The way I see it being done is to use a bot running on the bugzilla server. On the bug's page have a "Join Chat" button which communicates with the bot telling it to join a chat room. Once the bot is in the room you have it log everything that gets said, and have it store it in a nice format that can get inserted into the web app's DB or storage. You could have the bot do the invites by specifying who needs to be there when you tell it to join, or you could do it by hand.
In response to Any Jabber Experts Around?
