AppleScript or Automator Workflow for Bulk-Converting Powerpoint Presentations to Keynote
I couldn't figure out how to get Automator to do it, but I was able to beat AppleScript into submission.  Just save the following as an Application in the AppleScript Editor, then drag the files you want to convert onto the icon.  It will prompt you to choose a folder where the converted files will be placed.

on open droppedFiles
    set theDestinationFolder to (choose folder with prompt "Choose destination folder") as Unicode text
    repeat with theFile in droppedFiles
        tell application "Keynote"
            open theFile
            set theSlideshow to slideshow 1
            set theDestinationPath to theDestinationFolder &amp; (name of theSlideshow)
            save theSlideshow in theDestinationPath
            close theSlideshow
        end tell
    end repeat
end open


(I don't really know what I'm doing with AppleScript. If there are improvements that can be made here, I'd like to know about them.)