As the name implies, gigabit Ethernet is a more advanced level of Ethernet networking and communication standards, gigabit supports a transmission rate of up to 1gbps.
Contrary to popular misconception, gigabit does not require special wiring and can be setup on common twisted pair cables (CAT5 and CAT6 are recommended).
Gigabit is gradually becoming more well known and many networks are upgrading to gigabit, albeit slowly. Mostly it is research institutes that are adapting it, because of cost constraints and issues with adaptability of LANs which have prevented it from exploding into home networks.
However once implemented, it is not too drastic a change as much of the old technology works well with gigabit and perhaps with improvements in its adaptability to LAN will see it becoming a popular choice.