We are adopting transracially. We live in a pretty diverse area with plenty of other transracial families (through interracial marriage, adoption, step-families, etc.). However, I only have a few friends of color and none are very close friends (yet). I've done a lot of reading on the topic and a lot of thinking. And while I do think that it's important for white parents to educate themselves about race issues and to make friends with people of color and expose their children of color to situations where their children are not "othered," I think there are other fundamental things that are more important. For example, lack of permanency is so detrimental to children that exiting from fostercare as quickly as possible should be the highest priority for anyone seriously concerned with child welfare. There is a thread here about that: http://www.mothering.com/community/t/1329733/fascinating-article-on-korean-adoption. And the book, Nobody's Children: Abuse and Neglect, Foster Drift, and the Adoption Alternative by Elizabeth Bartholet, addresses the issue in depth.
Furthermore, all parents ought to educate themselves about race issues so they can raise anti-racist children. In my opinion, the emphasis on transracial adoptive parents to learn more about race than other white parents is misplaced. In order to combat racism and to provide an environment where all children thrive, ALL parents must learn to reject racism and raise children who reject racism as well. What's worse: children of color who have lost their racial identity and/or suffer from low self-esteem as a result of ignorant yet well-meaning "colorblind" parents or white children who continue to ignore white privilege and prepetuate racism at every turn, blindly oppressing people of color? I'm not sure which is worse, but they're both problematic and I do not believe that race-matching in adoption will solve either problem.
In my own path to adoption I have seen firsthand many other issues that I consider to be far more fundamental than race - drugs, poverty, mental illness, abuse, neglect, and instability. Children deserve stable, safe, loving homes and they deserve them now! They can't wait until we live in a post-racial society.
However, regarding race, I suggest you read these:
Inside Transracial Adoption by Gail Steinberg and Beth Hall
I'm Chocolate, You're Vanilla: Raising Healthy Black and Biracial Children in a Race-Conscious World by Marguerite A. Wright
Weaving a Family: Untangling Race and Adoption by Barbara Katz Rothman and William Loren Katz