Heh Eppie mentions scrapebox in his post. Never thought I'd see scrapebox mentioned on SEOmoz.
Anyway, it's a good post. Looks like blog commenting is still a viable link building strategy.
I'm going to say that it was many factors, not just blog commenting.
Here are some things that I noticed:
The domain was not an EMD but was a domain that included the keywords and had "quote" as a related term on the end. Google seems to be giving some kind of penalty to emd's which is probably why the domain was not an EMD.
If we look at the seomoz 2011 ranking factors you'll see that the correlation data shows that emd's have had a significant drop while partial match has had a significant increase, the question to me is what would be better if you wanted to rank for "auto insurance"
Autoquoting.com or autoinsurancequoting.com
I'm going to assume both are ok but the second option is going to rank a little higher.
Another thing that I noticed was that the site was linking out to an authority in that niche which should always be standard practice these days.
Also the site has over 150 google +1's and other social influences.
Building 10000 linking root domains over a period of 3-4 months is impressive. Those 10000 links are not just links, they are indexed links. I'm going to assume the reason for this was for the diversity. IP, no follow/do follow, anchor text, pagerank, types of links, and so on.
The real links come from those pages that have high authority and trust, IE a followed link on the BBC? You can't ask for much better than that.
Whoever did this had a plan of action, and it worked. I have always said that if you can crack google, you will make millions, why? because you can rank for whatever you want.
A true SEO does not care about blackhat/whitehat, they care about what works and what makes money. Even if that method only lasts for a few weeks, it does not matter because it can be repeated as many times as needed. What really matters is, is profit greater than investment and if it is by how much. Are the risks worth it? It's all about making money, nobody does seo for any other reason.
I personally like to learn from other people's success, not very often do url's get shared like this and for that reason I'll be doing a lot of testing with similar methods.