Do you think Apple know how many Hackintoshes are running?

I rather suspect they do.

Although the cheese-grater Mac Pro allowed you to swap components, Apple know how many they've sold. So anything else running an unusual hardware configuration must be detectable.

As Hackintoshing is really not for the faint-hearted, and it's very much a minority pursuit, I guess Apple have decided ignoring the issue is better than publicising it.