Very cool idea! Looks great! Here's a couple of critiques:
1. On the main graphic in the middle of the page where it says "Matchio is The best way to buy and sell your books locally. Period." the letters run together when I view it in Safari 4.0.4
2. On the very bottom, the "Learn More" section, I feel that this is kind of an unnecessary use of JS animation. This section is asking for feedback, and provides useful links so if you don't expand it you might never see this info. I would just keep it expanded.
3. Everything under "Feedback" in the learn more section does the same thing.
4. Privacy policy and Terms of Services links don't do anything (I'm guessing they already know that though)
5. I also noticed in the source that there's a lot of inline Javascript, some in using JQuery, some not. I would try to keep it consistent and I'd throw it all inside of $(document).ready() to keep the markup cleaner, plus everything inside here will be ready to be used immediately after the DOM is loaded.