Doesn't this already exist?
http://en.wikipedia.org/wiki/Power_over_Ethernet
1. PoE devices are not common.
2. Ethernet port will never be as ubiquitous as the power socket.
3. PoE 2009 is rated 51W max, macbook adapters are rated 60-80W (45W for Air).
4. Say future PoE comes out with 110W rating, Apple can't and won't trust all vendors to follow the standard to eliminate something as important as the power source.
If the PoE does not eliminate the power port, it adds nothing to existing macbooks.
And it is not optical and it cannot drive a display. I think this patent is to combine power and Intel's Light Peak.