Planet13 - 6:57 pm on Jun 30, 2011 (gmt 0)
Inbound contextual links from blogs with strong domain authority and very on-topic content do work very well for me.
I wonder, if you are going to do guest blogging, it might be better to do it on a post that DOESN'T allow comments.
If I remember correctly, comment links that are nofollowed still diminish page rank that flows through the links that ARE followed.
I'm guessing that while one might have the only follow link on the page, if there are a hundred nofollow comment links, well, it might not be of much benefit...