From a press release from Sumitomo:
Sumitomo Electric Industries, Ltd. became the first company to receive Intel Corporation's Thunderbolt certification for the Thunderbolt optical cable and started mass production. Based on Intel's Thunderbolt technology, this new Thunderbolt optical cable allows data transmission over long distances.
The matter was commented on by us in September 2011. Optical fiber cables can be up to 30 meters long and provide the same 10Gbps transfer speed, even if they are rolled up or ?stapled? 180 degrees (you lose a little, but , overall, very similar performance). The cables are the same thickness, the connector being a little longer. Anyone who already has a Mac with Thunderbolt ports need not worry: they are compatible with copper cables (current) and those with optical fiber. (MacRumors)