You can add any page to your watchlist, in which case you will receive an e-mail notice when someone else makes a change to that page.
To watch an article simply click on the watch tab at the top of the page. Click that same tab on a watched page to unwatch it.
There is also a checkbox under the "Summary:" line on the article editing page which allows you to watch a page.
Follow the my watchlist link in the upper right corner of any page to view and manage your watch list.
See the watchlist tab in my preferences to control your watchlist.