Huh? Where does this come from you ask? Well from no less than Arvind Narayanan's Randomwalker's Journal. In April 2007 Arvind published a study on the effects of coffee consumption in the workplace titled, "The Calculus of Caffeine Consumption".
The bottom line . . . apparently coffee can work for you if you have time-bound work, especially if it's work where close attention is required, but if you work creatively with no time restraints, coffee consumption may actually interfere with your productivity. At least that's how I read Arvind's study.
So check it out and let me know what you think. I'd love to see comments on this. In the mean time, you see that cup of coffee at the top of this post? It's empty.