i guess.
but you still couldn't cache as much lol.
depending on what you do of course...
I think Cache would still be important.
For example:
My internet connection (fiber) is 100MBPS
Most speed testing websites cant even match my connection, either because they are on a slower connection, or because it ends up running through a slower server.
Since a lot of servers out there are on a slow connection, I use Google Web Accelerator, since it tends to be able to access things better.
But, on faster servers, like Microsoft, I do notice quite the difference between Fiber and Cable.