In many conversations I have had regarding the source of hot peppers heat (The Heats), the understanding it is the seeds.  Be this notion common it remains inaccurate. In that this site is dedicated to the dissemination of knowledge of the heats, I would be remiss to not address this misnomer. To be sure, the source of the heats (Capsaicinoids) resides in the pepper pod rather than the shoots, leaves, roots, and seeds so this is the place to start our journey. The pepper pod comes in a variety of types having a variety of shapes and sizes.
The pepper fruit is composed of several structures including the stem (pedicle), the calyx (the green leafy crown at the top of the pod), and the pod. The pod consists of the pericarp, a,k.a the flesh (consisting of the endocarp (inside part of the flesh), mesocarp (middle part), and the exocarp (skin)), and the placenta. The placenta is the white colored material in the center part of the pod from which both the seeds and capsaicinoid glands are produced. The capsaicinoid glands are the structures that produce the Capsaicinoids, the chemicals responsible for the heat. These glands produce delicate little sacs filled with Capsaicinoids called vesicles.
Now that the seeds and the vesicles are produced in the same locality on the placenta and as the vesicles are easily ruptured they will tend to burst from mechanical stimulation (cutting the pod open for example) and coat the seeds. This is why when someone happens to place a seed in their mouth the seeds will invoke the heat sensation. The seeds are not the source of the heats, however, the placenta is. That being said, the pericarp in some species does contain Capsaicinoids thus will be hot. For example, I have recently had the pleasure of eating some of the fruits from my overwintered Bhut Jolokia. These pods did not contain a placenta for some reason (another post to be sure) but were still very hot. In fact, Nowaczyk et al.(2006) investigated the capsaicinoid contents an interspecific hybrid (Capsicum annuum X Capsicum frutescens) and found that the pericarp did indeed contain Capsaicinoids although at consistently lower concentrations than the placenta.
[1] Nowacyzk, P., Banach, M., Siwicka, J., Nowaczyk, L., Polish Journal of Nutritional Science, 15 (2006) 37-40