Jill (Cheryl Contee) says it very well. Here's one quote from her April 12 JJP post, and then please go check out the original.
The step backward then is the misunderstanding, the lack of connection of race to what happened. The bewilderment I see in white people’s eyes as they ask — how did this even happen? They are shocked! Shocked, confused and dismayed! The Trayvon case is not shocking for African-Americans. Infuriating, yes. Disgusting, yes. But sadly…so sadly not shocking. Ok so white folks, just so we’re all clear — this happened because unlike your kid (or you), Trayvon was not white. And this kind of thing has a way of happening to not-white people sort of regularly.