I find it hard to believe that this "Cant be done". I had a NOKIA phone in 2005 that was able to do this! You set certain contacts into groups, then you created "ring profiles"... for instance "Important people only" would be mine... and you'd set it to send all calls to vm *except* those who were in the "important people" group. Those would ring through.
If Nokia could do it 7 years ago, I am confident apple can.
Also... Droid has an app already that does this as well.
My issue is... with all the additional things that phones do now (tweet, facebook, foursquare, words with friends...) I'm getting alerts like crazy... which is fine but at 1am I'd like to silence the alerts without silencing the whole phone in case of work or emergency. And I dont want to manually turn off the alerts for each of those programs each night either.
There's got to be a way. Droid does it, Nokia did it in the stone age. Somebody make it happen!