Then I realized that Adobe Photoshop CS3, Address Book, and Apple Script were the same way. Coincidence?

(The new Adium binary is already in place in the screenshot above.)
This should be a warning to the devs to fix whatever alias or automatic script or whatever it is that's wiping stuff out in /Applications. I've been using Macs for well over a year, and I'm no nublar when it comes to computers. I would notice if there was something on my system wiping out applications.
Fortunately for me, Address Book, Photoshop CS3, and AppleScript are replaceable.