How do you protect your core network from wireless attacks?

Recently a wireless security blog post was published advocating an inner layer of defense such as a wireless intrusion prevention system (WIPS) to protect the core network from wireless attacks. This is because the integrated security mechanism provided by the wireless LAN cannot protect against many different types of attacks such as rogue APs, unauthorized client connections, ad-hoc networks, MAC spoofing and many other attacks .

What is your experience with a wireless intrusion prevention system?
Do you think security integrated with the WLAN infrastructure is flawed?
Do you agree with the blog’s point of view?

I did not quite understand your comment. I would love to hear your views about the wireless security blog post.