The functionality of this widget is close to what I was looking for.
I'm using WP 3.1.3 and Weaver Theme 2.0.
I could not get the widget to work.
It only gave me the option of using widgets already installed in the primary widget area, not the "invisible" widget area. So I moved my desired widgets (categories and recent posts) into the "primary" area, but it still would not give me both options.
I even closed the widget setup and went back in. No better.
I wanted a 2-tabbed widget to switch between categories and posts. But this one simply would not pick up the "Recent posts" widget.
It would be great if it did. http://ssnet.org