Software
Here are two Automator actions I created that will take selected images from the Finder and create a Keynote slideshow from them. In addition to the “Create Keynote Slideshow” action, the “Automagic Slideshow” action will automatically export the slideshow to a QuickTime Movie. Requires Keynote Actions from Automator.us (included) and GUI scripting (Universal Access) enabled.
After downloading and extracting the zip archive, copy the Keynote Action Pack to your iWork folder (most likely /Applications/iWork ‘06). In order for the automatic slide titling and automatic QuickTime export to work, you must enable GUI scripting by opening the Universal Access panel in System Preferences. Place a check in the box at the bottom of the window where it says “Enable access for assistive devices.”
To use the Automator Actions from the Finder, copy both workflows to ~/Library/Workflows/Applications/Finder. With that complete, you’re ready to use the actions. Browse to a folder where you have a bunch of image files, select the images you want in your slideshow, then right-click and choose Automator->Create Keynote Slideshow or Automator->Automagic Slideshow.
If you wish to change some of the settings, such as the template used in Keynote or the slideshow resolution, just open up the actions in Automator. I have tested these actions with iWork ‘06 only, so they may not work with earlier versions of Keynote. Let me know how they work for you.
Download: Keynote Automator Actions.zip