Unsanity has released a 'haxie' (their term for an OS X hack) to take care of the #1 help request here at macosxhints.com -- disabling bouncing dock alert icons!
If you're tired of the Mail.app icon bouncing onto your screen when it can't connect, or the Explorer icon bouncing to let you know a page has changed, you need Dock Detox. It quickly and easily disables the bouncing dock icons (except for Classic applications), and best of all, it's free!
If you decide you don't want it any more, simply log out and log in again and it's gone (I imagine you could also kill its process ID, but I haven't tried this).
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020102182714675