+Pete Meyers has written a short article on Exact-Match Domains (EMDs) for SEOmoz.org.

It's a subject I find interesting, and so should anyone working with affiliate marketing or SEO. You can find a summary along with my thoughts below:

The correlation data at SEOmoz has shown a declining impact of EMDs on ranking.
The keyword here is correlation (not causation), more on that below.

EMDs had a solid drop in total top-10 rankings after the Penguin update, but that drop has recovered somewhat since June.

Ranking for PMDs suffered a serious decline after the Penguin update and has only continued to fall.
PMDs are Partial-Match Domains (buy-widgets-here.com would be a PMD to the query [buy widget]).

One thing to remember when reading an article like this is Correlation vs. Causation. +Pete Meyers addresses this matter in the article, but I think you should be very careful about writing off EMDs too fast, which is what I think some people will believe you should after reading this article.

To take an example one could imagine, that the reason EMDs and better rankings correlated more in 2010 than in 2012, is simply due to a greater proportion of the people working with SEO used EMDs back then.

Another example to look at is the reason EMDs dropped in rankings after the Penguin update. This could very well be caused by the assumption that many of the people who use EMDs in mid-2012 are also more prone to be using overly aggressive methods which the Penguin update was aimed at.

I believe EMDs (2 dashes or less) will continue to have a small but significant edge over regular domains. Google can’t just pull the plug on EMDs as many brands naturally use EMDs. The challenge is to convince Google that your EMD is also your brand.

I allow myself to rewrite a quote by +Tom Rusling: "Until you have data that backs up Google’s SEOmoz's claims, it’s better to not make a move."
Shared publicly