Aaron D. Campbell

Upcoming Posts Widget acts very much like the recent posts widget, but displays 
scheduled posts instead of published ones. Requires WordPress 2.8+
You may also be interested in WordPress tips and tricks at <a href="http://wpinformer.com" rel="nofollow ugc">WordPress Informer</a>

Upcoming Posts Widget

A widget that displays a list of scheduled posts.

rickacc

Linked Future Posts Widget acts very much like the upcoming posts widget by displaying 
scheduled posts instead of published ones, but includes a link to each post (using slug/post name). Requires WordPress 2.8+
Use this plugin in conjunction with the Future plugin from Marion Sudvarg to create a Post Grid of scheduled events and a list of scheduled 
events on the post page. Events that change from scheduled to published status will automatically be removed from the grid and list.
Linked Future Posts Widget is a derivative of the Upcoming Posts Widget plugin created by Aaron D. Campbell.

Linked Future Posts Widget

A widget that displays a list of scheduled posts with links to the posts.

Upcoming Posts Widget vs Linked Future Posts Widget