Fernando, I’m definitely not convinced the solution to all the use cases you’ve shown is an IM buddy list and don’t see anything about having a central contact database with IM info being targeted at hackers. All the tasks you mentioned are about finding a person. Are you saying that scanning through a huge buddy list is comfortable?
In real life when you’re looking for a person, you use an addressbook. That’s what the gnome desktop needs. A separate addressbook application for you to manage your contacts. As currently implemented in the EVo integrated contacts component, it would contain IM info as well. So when your nympho Alice wants to scan though her contacts, she can do that in the addressbook as well as she would in the buddy list. However if she’s actually looking for someone particular she would have better ways than scanning.
You have to realise people have a LOT of contacts (A nerdy disocial home creature like myself has about 50 personal contacts and that number will be a lot higher for “normal” people). Especially in the corporate environment with central contact repositories of employee colleagues and individual business contacts. I’m convinced the buddy list for instant messaging is redundant.
As for IRC-like group chat with no real concept of identity, that you’re possibly targeting with your nick changes use case, I don’t know. Not being able to reliably relate data to a person sounds like a nightmare. I don’t see buddy list providing any solution though. I have to check how the IRC plugin in gaim really works but I’d be surprised it would deal with people changing hosts and nicks.