Agreed, I've taken it before a race before and I didn't really feel it had any effect, although obviously I can't say it didn't. Having caffeinated drinks during a run however at least psychological perks me up.
Marathon Talk had a training talk section about it ages ago linky.
They suggested to get the maximal effect you should abstain from caffeine a week or so before the race. There's also some mention that taking caffeine in the form of coffee might not be as beneficial as other chemicals in the drink might dampen the caffeine effect. The simplest way to take caffeine is in caffeine tablets (Proplus etc) but then there is the argument that you are then using caffeine, even though it is a legal drug.
Edited: 23/08/2012 at 13:40