The following screencasts produced for WordPress.tv offer an excellent overview of the platform in convenient 2-3 minute podcasts.
The Basics
Introducing the WordPress Dashboard
Using Quick Edit and Bulk Edit
Adding Images or Media to Posts
Adding Categories and Tags to post
Managing Categories After the Fact
Arranging Links into Categories
The Sidebar
Authors Widget (slightly different than Author Avatars widget)
Flickr Widget (slightly different than Flickr RSS widget)
Recent Comments Widget (slightly different than ACU Recent Comments widget)
Advanced Tips
Setting Posts or Entire Blog to Private
Setting Your Discussion Settings
Getting a Post Out Quickly with QuickPress