On one of the QRP mailing lists, there was talk about how minimal you could make a QRP transceiver. Several ideas were tossed around, but then Chris Trask, N7ZWY, nailed it.
The Gnat 1 uses a single 2N2222. The parts list includes values for 80m, 40m, and 30m versions, and the documentation even includes a PCB layout. Kits may also be available soon.