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Black tea contains about as much caffeine as Red Bull (per liter). Admittedly less than coffee, but hardly minimal. http://en.wikipedia.org/wiki/Caffeine
Comparing caffeine content in tea vs coffee is a tricky argument to make. The caffeine content in tea varies on many factors, including oxidation level, steep time, and leaf agitation. On average, the amount of theine/caffeine in a cup of tea is much less than that of a cup of coffee.
Here's another source: