Canonical URLs

The Big Three search engines recently announced support for a special tag to specify which copy of duplicated content on your site should be considered the canonical or "official" one, so they know that that's the one they should add to their indexes. Here's more info from Google, Yahoo! and Live Search.

Duplicated content can easily appear on Drupal-powered sites when URL aliasing is used, as the node will be available both at the aliased URL and at the node/X one. If you're using a node as your front page, then there's three places it could appear. And then there's the whole www. thing…

A canonical URL module would use hook_nodeapi() when $op === 'view' to add the link tag to the header. If the node being loaded is the front page, then the href attribute will be set to the Drupal installation's front page. Otherwise, the result of url('node/' . $node->nid, array('absolute' => TRUE)) will be used.

Someone else write this, pl0x. I don't want any more modules to maintain, or to have any more fights with CVS.