Ron Zvagelsky

Monthly grid view calendar widget highlighting archived and/or future posts.
Additional Features:
<ul>
<li>Popup details for each date with posts</li>
<li>Optional details include post author and comment count.</li>
<li>Ability to show posts by post type, category, specific taxonomy and/or term</li>
</ul>
<a href="http://presshive.com/plugins/wordpress-blog-post-calendar-plugin" rel="nofollow ugc">For more information or to request additional features, please visit the plugin page</a>

Blog Post Calendar Widget

The Blog Posts Calendar Widget allows you to display your archived or future posts in a calendar as a sidebar widget.

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.

Blog Post Calendar Widget vs Upcoming Posts Widget