At 400 megabits per second, FireWire is 40 times faster than 10Base-T Ethernet, and 4 times faster than 100Base-T. The only Ethernet spec faster than FireWire is Gigabit Ethernet (1000Base-T), now standard on all Macs, but still an option for many PCs (like FireWire).
Today, Apple released a preview version of IP over FireWire, useful for networking and clustering solutions. It can even be used for temporary connections to the internet using Internet Sharing. It’s interesting if for no other reason than that of future possibilities in networking.