Apple xserve cables:
http://www.cselex.com/apple-xserve-cables.htm

You can use fibre optical cables with these devices for long distances - but you dont have to,
the SFP plugs can take optical transceivers.

http://www.apple.com/xserve/raid/fibre_channel.html

For connecting over longer distances Apple?s card accepts long and short haul SFP (Small Form Factor Pluggable) optical transceivers for use with fiber-optic cables that can extend over 500 meters. This is particularly useful for organizations using Xserve RAID to back up or archive critical data.