Read on TechCrunch that you can reverse the scrolling direction:
You can find the checkbox to set the scroll direction to what you’re used to under System Preferences > Trackpad > Scroll and Zoom. Look for the “Scroll Direction: natural” option.
That’s fine if you have a trackpad, I don’t. So what’s the fix for if you just have a mouse? I went to the Apple Store yesterday and put that question to the guys in blue, none of them knew how to do it. They’re going to email me the answer when they find out. I’ll update here when I hear back.