Well, it's easy to accidently remove something from the Dock, and things could appear that you did not place there, if it's reverting to the defaults. One way to make it revert is to remove the com.apple.dock.plist file from your preferences folder. But if you did not do that, I'm at a loss.
Have you tried it again? Remove iChat by dragging it off, and restore WOW by draggin it to the left side of the dashed line. Restart immediately and see if those changes were saved. If so, then the previous behavior was likely caused by you accidently.