GREAT post! I, myself, got tired of explaining how it works. This thread was definitely needed, perhaps a mod could make it a sticky?
@brad: in order to achieve 5 volts from 14500 batteries, they need to be wired in parallel (positive end to negative end), producing a Vt of 7.4 volts. This is usually regulated down to the required voltage.
Additionally, each 14500 battery is (usually) rated around 900 mah. In order to achieve 1800 mah from two batteries, you need to wire them in parallel (both positive ends tied to together, both negative ends tied together). However doing so will only net 3.7 volts (voltage is constant in a parallel circuit, current is constant in a series circuit).
Using 2 14500 batteries in series will net roughly 900 mah, still a lot better than any standard ecig battery produced.
However, using a step-up converter could solve the problem, boosting the 3.7v output of 2 14500 batteries to the voltage you require. But that adds circuitry that you are trying to avoid.