Actually the one thing that DOES reduce latency is never mentioned - the network you are connecting to.
Smaller players like Internap charge you more, in return they deliver the lowest-latency bandwidth possible. They do this by contiuously tuning their BGP (routing) setups and make sure to buy direct routes to most big suppliers, like Level3, ATT, NTT (Japan), Cogent, TeliaSonera etc. etc. Thus the mix you get, is a tuned mix of 5 to 7 other suppliers.
The difference you are speaking of is a small number of millaseconds. Maybe the difference between 50 and 80ms. this might make a difference if you are doing something like trading stocks... but for most webapps, your database is way slower than that. 20ms lag in loading a http page is not going to be noticed by anyone.
Smaller players like Internap charge you more, in return they deliver the lowest-latency bandwidth possible. They do this by contiuously tuning their BGP (routing) setups and make sure to buy direct routes to most big suppliers, like Level3, ATT, NTT (Japan), Cogent, TeliaSonera etc. etc. Thus the mix you get, is a tuned mix of 5 to 7 other suppliers.