Block Web Page Printing @ Gid`s net.
The content of this page can not be printed with
any of the usual easy methods...
All you get is the header, and footer info ie..
page name/# at top, and url/date at the bottom.
None of this text well be printed.

I have tested this in IE, Chrome, Firefox, and Safari.
Simply place the folowing code in the head of the page you don`t want to print,
or add it to the style sheet of your site if you want None of your pages to be printed.

<style type="text/css">
@media print{
body{display:none;}
}
</style>

Source: http://webdesign.about.com/od/advancedcss/qt/block_print.htm

As my source points out.. "Please note, there are ways to get around this functionality - this is not intended as an absolute prevention of printing Web pages."