In the General Macintosh category, I found this on a support page from one of my much-needed developers:
For DP users, this might be something to keep in the back of your minds especially for those using QuiKeys or similar. Once DP is ready for Lion, everyone might want to pay special attention to their Command Bindings.Apple has reversed mouse scrolling from previous versions of Mac OS X. For example, scrolling down will move the page up, and scrolling right will move the page left. This option can be changed in System Preferences > Mouse > Un-check Scroll with finger direction.
Why? Because, apparently, "right" is the new "left" and "up" is the new "down".

Feel free to add your findings in this thread as you see fit.