Exchanges have been moving to electronic platforms over that past decade, but the last several years have seen it drastically increased. The live open outcry exchanges still offer some advantages, I think ulitmately it will difficult to completely do away with them. I would guess that 75% of orders are now executed electronically, I would venture to say that this will go to 90% at some point. I used to work at the NYMEX (crude oil, natural gas, electricity, coffee, etc) which was almost entirley live pit trading, from what I hear over the past three years, a huge % of the orders are electronic now.
To answer your question directly, the newer electronic platforms offer quicker, fairer order exectutions. For institutional investors and traders this has both benefits and drawbacks. For retail investors, its a good thing.
