Much like the Killzone 2 demo, Sony will only be making the demo for Patapon 2 available for pre-order customers in the United States. Of course, you could always make a European PSN account and grab the demo that way, but this is kind of a drag for people that want to try the game out before making a purchase.
The demo will be available to pre-order customers at GameStop and Amazon.com. This strategy always confuses me as the people willing to put money down on the game probably don't need a demo to make their decision. The game is also good enough to sell itself with a decent demo. Why not make it available to all on the PSN?
Granted, you could just go drop $5 at the retailer and get that money back if you decide you don't like the game, but it doesn't serve to promote the title if you have to put that much effort into trying it out.
Patapon 2 will be released for the PSP on May 5, 2009. Chaka-chaka-pata-pon... provided you've got $5.