Quote:
Originally Posted by
Darth Llama 
Thunderbolt was envisioned with fibre channel, but intel found that could obtain the target 10Gb using copper alone, as I remember the discussion it seemed that they still intend to make it a fully fibre channel connection and have the methodology to acomplish this currently with a massive increase in throughput, but copper allowed them to get production ramped up faster.
You're right on the fact that they originally were going to use fiber optic cable, and then they switched to copper. However, this didn't impact performance at all. Copper does just as well, but with one disadvantage. Lengths over a certain distance show a dropoff in performance. The fibre optic thunderbolt cables are only useful for long distance (over a couple meters) connections, otherwise they don't have a speed advantage over copper. That's why Intel is making the copper cables first, since they get the same performance for a smaller price, and most early thunderbolt peripherals won't need long cables (monitors, eGPUs, storage bays, etc.)