For those of you who are having troubles, I just want to talk through the process again:
First, copy the script from jeremybrown's post into Script Editor:
http://forums.omnigroup.com/showpost...9&postcount=10
Try to compile the script. You may be asked to show where the application Omnigraffle is. If it doesn't compile, the issue is typically the back to front ordering line, which you can comment out by placing a double hypen at the beginning of the line (--):
-- set children to bottom to top ordering
Then Save As an 'application' and place where you like.
When you want to create a new sitemap, just drag your xml file onto the AppleScript Application and it will load OmniGraffle and start creating the document in the frontmost canvas.
It can take a little while if there's a lot of pages so give it a few minutes.
Hope that helps someone!
Shines