Hiding Take Five's Dock Icon
Can I run Take Five without a Dock icon?
Yes, open Preferences by clicking on the gear icon in the main window. Then uncheck the “Show Dock Icon” setting and restart the application. After that, Take Five will only appear in the menu bar.
If you choose to hide the dock icon in Take Five, and have the application in your startup items, it can sometimes cause the dock two display two icons. See this article for more information: http://support.iconfactory.com/kb/twitterrific/why-i-am-seeing-two-twitterrific-application-icons-in-the-dock-mac