It is specific to Drupal from what I can tell. There are a lot of pages out there that use it. When you remove it the pages does not change. This is something that drupal is putting on your pages and is creating duplicate content. I would recommend using the canonical tag.
We do use canonical tags now I am wondering if our rankings will go up. We just started to use cannonical tags a week ago, but we have more and more pages being indexed daily. Is there a way to check if there is a possible penalty?