One of the more powerful features to have been introduced to Illustrator as of late is the Recolor Artwork feature. When it was introduced in CS3, it was called "Live Color" but thankfully, Adobe dropped that name and now officially refer to it by its more descriptive name: Recolor Artwork. Granted, the feature itself is incredibly complex, but that's because it just does so much, You can't really demo it unless you have a specific task you're looking to accomplish.
On the User to User Forum, someone asked specifically how to accomplish a task, which was really a perfect example for showing one specific part of the Recolor Artwork feature. So I recorded a quick little movie, which I think can help people get a better idea of what the feature does and how to use it -- at least for this one specific task.
Because the Recolor Artwork feature works only on selected artwork, I also added a bit on defining a custom action to help automate the process of unlocking and selecting the art.
Recoloring Artwork in Illustrator CS4 from Mordy Golding on Vimeo.
What the video doesn't show is how to re-lock all of the art once the color edits have been made. To address that you'd actually choose View > New View when you first open the document. Then, after you've completed the color edit, simply choose View > New View 1 (or whatever you've named your view).
As an aside, this tutorial will work in CS3 as well.