Back in February, Google announced their support of the Canonical Link Rel element, and it was also announced that Yahoo! and MSN would soon follow suit. If you’re not familiar with it, think of the Canonical Link Rel element in terms of a 301 redirect–you can tell the search engines to ‘focus’ (though in this case, there’s no redirect) on a page you specify. It is placed within the head tags of a web page, and is a great remedy for the duplicate content stigma.
Essentially it looks like this: