Here's a post someone made about 6 years back: "Why Trillian Sucks"
Not all things open source go the way of, say, Ruby on Rails.
Right now when I see Jabber instant messaging mentioned I'm looking at an "ecosystem" of poorly written clients that, aside from the Google Talk system, haven't gained much tracton. I suspect that Google Talk hits the sweet spot because it integrates email contacts with live IM, voice calling (which, apparently, no other Jabber client has), reliable file transfer, and the fact that it was integrated into an existing product, which means at launch it had a few million users.
As I see it, the instant messaging world has stopped moving forward. No major, innovative improvements have happened for a few years. So, why is Jabber so far behind? They apparently still don't have a video / audio chat standard, or if they do there's no thrust to get them implemented into popular clients.
I guess what Jabber needs is an innovator: someone to blast into the Jabber instant messaging space, and drop all those features people are waiting for (audio, video, emoticons -- features regular consumers are waiting for) and leave the rest of the Jabber community in shambles.
Things on the 'net seem to work best that way. Firefox's destructive (marketplace-wise) rampage across the Internet is a testament to that. For the first time in a long time Microsoft started ramping up Internet Explorer development when they realized Firefox was here to stay. Why not the same with Jabber?
For now, though, I'm comfortable using three separate instant messaging clients. I got the resources to spare, and I gave up on Trillian a long time ago.