I know that blog post has sub domains, but what are links like coming from blogpost sub domains? do every one count as a vote?
You mean, BlogSpot/Blogger? Google does index them, as you already probably know. The importance of outgoing links from them, which are incoming links to some site, depends on the incoming links to those Blogger posts, whose importance depends on the incoming links to those incoming links to Blogger posts..... Simple (?) answer is: As long as your Blog post is not a spam link home, and as long most of the incoming links to the blog posts are not from link farms, it should help you.
you mean url.blogspot.com, blogs especially blogger can help boost traffic for the site and I know that google own the blogger. It easily indexed from the search engine
if u have blog post link than it will help more than link exchange as u r getting one way link. as u know that google gives more weight to one way link than reciprocal links. as u have links on blog post and your content is informative than u will get more weight of those links.