I found blogs that they put the link of matt cutts on their blogroll. Anyone can explain that is that purpose of putting matt cutts blogs on their blogroll.
I'll be charitable and assume that they think the blog is interesting and useful and that people who read their bog will like it. If I was being uncharitable I'd think they were complete idiots who thought there was some SEO benefit from it.
There are 4 typef of people who put a link to Matt Cutts blog in their blogroll. 1. They do because believe in the positive effect for SEO by linking to the (they think) authoritative source. 2. They do like what Matt Cutts said personally 3. They are Matt Cutts fanclub and never care what is Matt Cutts talking or showing, or even who is the Matt Cutts really! lol 4. They have been asked from Matt Cutts friends to put the link on their blogroll, for free of course. lol