Our team previously used Adium as our chat client and it had a great feature for message notification on Macs: in addition to the red message count badge, the icon could be configured to “bounce” (once, ‘n’ times, for ‘n’ minutes’, every ‘n’ seconds, …).
I liked it because I like to keep the dock hidden (to save screen space) and I NEVER notice the red dot on the icon at the top of the screen.
How hard would this be to add to MM? I’ll give it a shot when I get a spare moment.