Psychonauts was one of my favorite games from last gen, and only a small number of people actually bought the game or, really, knew that it existed when it came out. Newly formed game developer Doublefine released it with the publishing "might" of Majesco behind them. In spite of it's poor sales, the game itself was quite brilliant. The setting and humor within it are top notch (with the back-to-back levels by the lake being among my favorites in all of gaming), and while the gameplay had some weak points here and there, it was still a genuinely thrilling and fun platformer.
Although it may be a bit of a poke to the ribs, but in order to get some extra interest (and some pre-orders, naturally), I would suggest that the original game (made compatible for the next-gen systems) be included as a pre-order bonus of some sort. This would be mainly for those people that haven't played the original and aren't quite sure what they're wandering into with Psychonauts 2.