wheel - 7:53 pm on Jun 23, 2011 (gmt 0)
The link back is what you're getting in exchange for the content so you should demand a link back. It's unlikely you'll even have to ask though, everyone knows the downlow on this, they'll assume you're getting a link.
Commonly these blog articles will have two or three links within the content of the article. Plus, the final paragraph is normally an attribution paragraph which includes a link like:
THis is a guest post by afreshup. Afreshup has been in the finance credit card industry for 20+ years and is presidend of Afreshup global domination inc. (where Afreshup global domination inc. would be a link to your website).
I no longer do in-content links when I get guest articles published, just get the one in the attribution. And my articles are long, page down multiple times to read it all. But I'm sure I'm very much an outlier on that.
Also, you should expect a low success rate on this. Maybe approach 10, convince 1. Again, this is good stuff, it's a barrier to entry for most. But I'm confident that 1 link from an authority blog is easily worth 10 to 50 low end blog links.