For some users, a bouncing dock icon is a big irritation. There is an alternate (and I would say more common) notification standard that is much, much less intrusive if it is possible:
See Mac Mail: http://img261.imageshack.us/img261/3491/dockgj7.jpg
See Thunderbird: http://www.zippydan.com/pictures/other/thunderbird_msn_dock_notifications.png
See Skype: http://www.zippydan.com/pictures/other/skype_ym_dock_notification.png
See MSN Messenger: http://www.zippydan.com/pictures/other/thunderbird_msn_dock_notifications.png
See Yahoo Messenger: http://www.zippydan.com/pictures/other/skype_ym_dock_notification.png
Another random application: http://deadlineapp.com/images/deadline_dock.png
