There are a number of ways to do it, but, none will always work. Here are the two easiest:
- if it’s a known finite set of websites: in your scraper convert each url from the normal url to the print url for a given site (cannot really be generalized across sites)
- Use the arc90 readability algorithm (reference implementation is in javascript) http://code.google.com/p/arc90labs-readability/ . The short version of this algorithm is it looks for divs with p tags within them. It will not work for some websites but is generally pretty good.