Virtually no modern wired networks use hubs anymore, they're for the most part switched. Unlike wireless networks where packets are broadcast freely in to the air, the switch checks the destination address and sends the packets only to the endpoint. There are some attacks like arp-spoofing and flooding which can defeat this, but they don't work well against modern enterprise-grade switches like you would find in a data center.
Have a bazillion karma points. I didn't realize that switching resolved that whole problem. This is why I continue to bring up stupid hypothetical situations on HN from time to time ;-)
Switching doesn't resolve the problem completely. There are a range of complicated attacks that could be done, but can be detected in various ways in a well run NOC.
