On Saturday I'll be giving a talk about my experiences with DNA testing to OGS Seminar. To start getting an appreciation of the topic I recommend the book Trace Your Roots with DNA by Megan Smolenyak Smolenyak and Ann Turner. I'm not aware whether a new version is coming, but you can find copies remaindered at abebooks.com selling at between $6 and $7US plus shipping. It's a deal.
To stay abreast of developments I scan the discussions on the Genealogy-DNA Rootsweb mailing list. You might also look at some of the links from the Wikipedia article on Genetic Genealogy.
"The Genetic Genealogist" is a fairly new blog written by Blaine Bettinger. He describes himself as having been using traditional genealogical research to learn more about his ancestry for almost 20 years, and he also has a Ph.D. in biochemistry with a concentration in genetics. The blog is aimed above the beginner level. I found it quite comprehensible, although a recent article had a Flesch reading index of 33, "teetering on the edge of unclear." This post is only slightly better! I find "The Genetic Genealogist" helpful so it's added to my links list.