Dunno if this is of interest to anyone but Adium was Leo Laporte's "pick of the week" in this week's MacBreak Weekly. He seems very enthused about it (understandably) and says it's now his most used Mac application.
The Adium recommendation starts at 1:06:30 and ends 1:11:25 (although it's also interspersed with recommendations for the open-source microblogging platform Laconica).