I think the surprising answer may be: not all that much. Look at how fast computers are these days. No one (except gamers and professionals) have needed faster

I think the surprising answer may be: not all that much. Look at how fast computers are these days. No one (except gamers and professionals) have needed faster computers in 5 years. Once we all got fast dual core machines with 4GB ram it's pretty much all been gravy. Mobile devices are starting to reach that level now. I don't doubt that there will be some very compelling applications for gigabit speeds, but I don't think it will be a revolutionary thing.