Sure, just find the + sign in the lower left corner of the dashboard and click. Now click the "Manage Widgets" button that appears next to what was the + (it's now an x).

A box will pop up with a list of widgets and just check the box next to the address book and the icon should reappear in the dashboard.

I get the dock and the dashboard mixed up and almost gave the the directions to replace it there which is just opening the Applications folder and dragging the address book to the dock and dropping it there It just makes an alias (shortcut) on the dock. I've always liked that since you can do this with any application.