I’m sure at some point in the future I’ll laugh about the days when two finger scroll down meant scrolling the page down rather than up. Today however,is a very difficult transition.
On Lion, the default motion you make when you scroll on the trackpad is the same motion you would expect to see if you were scrolling on the screen.
If that isn’t the biggest hint into the future of the Mac, I don’t know what is.
Of course you can revert to the old way in the system preference, pictured below: