The short answer is no, it shouldnt... However I have had experience with nofollow links actually being followed and the pages they link to indexed. While it probably carries less weight I do tend to think Google counts nofollow links in some way. This of course is just my theory and open to debate
yes same exp. with me. I even think it also gives some pr juice, abit but still. So the question: should I allow my blog to have comments field at all? since I find allot of people are using it to advertise their website