After installing Lion on my mac, the scroll on my mouse is now reversed and I find it very awkward.
Is this a "feature"? How can I revert to the normal method of scrolling?
This is indeed a "feature". It's called "natural scrolling", and was likely done to increase the similarity of the experience between iOS devices and OS X. You can turn it off from the mouse settings panel in System Preferences by unchecking "scroll direction: natural".
(Image from post on Ask Different)
After first installing Lion, there's a screen you have to go through before proceeding:
(Screenshot from this Engadget review)
It does explain how to change the toggle this feature if you don't care for it.
Roaming around the System Preferences pane in Lion will reveal that a great many of the new Lion features can be disabled or altered in some way. Which is nice, since I've found I only like half of them. Terminal commands are available for many others.
There's also a nice app, Lion Tweaks that - as the name suggests - handles some of this for you. The site for the utility is http://ifredrik.com/applications .