But OS X does look the same as it did years ago, unlike Windows which went through five looks (2000, XP, Vista, 7, 8). It's not as if Adium has any design elements that could possibly age - it's a standard OS window with a customisable HTML message list.

Edit: I just realised that I have hidden the ugly message window toolbar. I'm not sure if it aged though - I already hated it on OS X 10.4 (when I disabled and then forgot about it).