How much caffeine is too much caffeine?

The Mayo Clinic gives a web page about common beverages and the amount of caffeine in them. I write this knowing of my now year-and-a-half Starbucks morning routine, JG going to the coffee pot in the employee breakroom, MP and his multiple cans of Diet Pepsi One nucleic acid, and Haworth Hiker's mere thought of drinking a caramelicious from Scooter's coffeehouse.

Click here for the Mayo Clinic's caffeine study.

As for me and my caffeine consumption: Guilty, as charged, your honor.