Nice.
But why "discuss" is no-follow link too ?

The normal link to this forum is on the left-side.

"Discuss" links below posts on the other hand automatically paste a "Re: url..." into the textarea using special IDs:
blog.outer-court.com/forum/?post_id=603

If you check this particular URL, you will see I additionally disallow indexing of this page using a meta directive:
http://blogoscoped.com/forum/?post_id=603

Why? So only the forum, not the pre-filled textareas get indexed.