Nintendo of Europe posted an item on their website today detailing a bug within the European release of Super Paper Mario. It's a bug that occurs when playing the game in UK English, German, or Spanish. After meeting Mimi in Chapter 2-2, if you talk to her before picking up the key that opens the nearby trap, the game will freeze. It's a tiny bug, and one that is easily circumvented by following the instructions NoE has included on their website. Despite that fact, the company still plans on offering a free replacement disc in the near future for anyone that would rather have a bug-free version of the game. Awfully nice of them if you ask me. I would have just sent a notice out via the website and possibly the Wii-mail system and been done with it. Keep an eye on Nintendo Europe's site for replacement details.
Super Paper Mario announcement [Nintendo Europe - Thanks Martin]