] This is called comment spam, we don't like it either, and
] we've been testing a new tag that blocks it. From now on,
] when Google sees the attribute (rel="nofollow") on
] hyperlinks, those links won't get any credit when we rank
] websites in our search results.

Right on. I am trying to think of downsides; certainly it will decrease the visibility of good faith link recommendations. It also means it may be harder to trackback to user identities from where they post with personal url. But these don't seem significant enough relative to comment/guestbook spamming.

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