Apple Script for converting a Keynote file to a folder of images. To use, create an Automator application and use an Apple Script block. Save the application to your desktop and you're good to go.

keynote-to-images.scpt

on run {input, parameters}
	
	-- Validate input
	if input is {} then
		display alert "No file selected!" message "Drop a file on the action to process the keynote." as warning
		return
	end if
	
	-- Declare variables	
	set fileName to POSIX path of (input as string)
	set fileName to do shell script "echo " & quoted form of fileName & " | tr ' ' '-'"
	set currentDate to current date
	set yearNumber to year of currentDate as string
	set monthNumber to month of currentDate as integer as string
	set dayNumber to day of currentDate as integer as string
	set folderName to ""
	
	-- build the folderName
	set folderName to folderName & {"Keynote-Export_" & yearNumber & "-" & monthNumber & "-" & dayNumber}
	
	-- Open keynote and export the file to images
	tell application "Keynote"
		set doc to open input as string
		export doc to alias {"Macintosh HD:Users:yourusername:Desktop:" & folderName} as slide images with properties {image format:PNG}
		quit
	end tell

	display notification with title "Keynote export done" subtitle "Completed"

	return input
end run