There has been a small change to the adium-theme-ubuntu made for maverick (a patch by om26er on freenode irc) that everyone can now check out on Lucid through my PPA.
What you should notice (and only notice) is that there was a change in the font. If you didn't know already, Gwibber and Empathy both use the same theme, but Empathy's font was noticeably smaller. This change probably won't make it into Lucid based on talks I've had with the maintainers, but if there is enough interest in this change based on the comments in this post, I will talk to a few of the maintainers and see what I can do.
To the left is the maverick adium-theme-ubuntu and to the right is the lucid one