WashingtonPost.com has started a new e-zine aimed at Black folks called "The Root." The timing is obviously coinciding with the premier of African-American Lives 2, premiering this Wednesday. Dr. Gates is figured prominently on the page, with a welcome video from him and several celeb clips from the PBS special.
Lots of interesting news articles, and the genealogical feature looks promising. You can post your tree by hand or by uploading a GEDCOM. It's a Flash app, much like the Geni.com and Ancestry.com. However, it's not clear whether you'll be able to share your tree with others and I don't see any feature to search other trees. So, I'm not sure why you would use this over something like Geni.com.