"Nofollow the links to your tag pages
If you've decided to keep your tag pages from being indexed, you might as well stop throwing link-juice at them on each post..."
This is actually broken if you look at the source of a post:
Sample from mine:
<div class="tags">Tags: Action,
As you see, it actually puts rel="no follow tag" instead of putting rel="nofollow".
This explains why all my tags are being indexed by Google despite my best efforts to prevent it.
Hope to see this fixed.
edit: duplicate post, sorry.