Apart from that entourage in disguise.
Guys, Mail already is Mail+Address Book+iCal. Sorta. It has many integrated features such as add to contacts and stuff but it's not a SINGLE application. Usually those features open iCal or Address Book (there are also features in iCal and Address Book that use Mail and each other such as iCal antendees).
Think of it like iLife and iWork.