I read an article today referring to a study published in the journal Epidemiology. Apparently if you only drink one cup of coffee per day, then your risk of a heart attack is greatest in the hour just after that cup. If you have more than 4 per day there is no correlation.
So if you are in an at risk group (ie. sitting around talking instead of manically exercising) and care about your health, then make sure you keep drinking heavily throughout the day.
This may be the justification I need for replicating my coffee equipment at work...
Rhys