Hi list,
  Just watched this piece:
    http://www.youtube.com/watch?v=8RFLIj4a2kw#t=29
  It's 60 minutes, so a bit sensationalised, but it discusses the role of 
fibre optic networks in stock exchanges and namely High Frequency 
trading, and some interesting solutions to the problem. Found it quite 
interesting so thought I'd share!
Thanks