That's a nice feature, but still looks half-baked for me. It's now ios6 and you still need to jailbreak your iphone to blacklist people harassing you with phone calls or imessage. What I do need is a blacklist feature which send to /dev/null people I don't want to talk to or receive imessage or sms from, and the DND feature looks more like a whitelist only available to phone calls. Maybe in ios 7 ? It seems like a basic feature and I wonder which Apple Developper Program rule prevent to develop such an app available in the app store.