I did not plan to wait for a Mark III, and had started making some sacrifices to enable purchasing a 5D Mark II, or perhaps a Nikon D700, but then I had an opportunity to purchase a very clean pre-owned 7D, and went for that, instead, which actually means I now have two 7D bodies.
Well, I did the math, and found that what I paid for the pre-owned 7D, plus where some original 5D cameras are currently priced, is comparable to what a new Mark II costs, so I am actually considering an original 5D, to finally be able to try full-frame for portraits and landscapes, primarily with a tripod, when weather-sealing, fast handling, and fast focusing are less important.
To be clear, I am not recommending that anyone settle for an original 5D, just offering my view on obsolescence. A well-maintained product still does what it did when it was state of the art, so the introduction of a newer model does not make its predecessor obsolete, if the manufacturer (or aftermarket) is still supporting it. If a 5D Mark II does what you need it to do, why wait for its successor?
Moreover, with the epic tsunami of 2011, the wait for a successor may be long.
Canon 7D/5D/40D/1D2N; Nikon F6, D700, FM3A, & Coolpix A; Canon 40mm 2.8 STM, 135L, 50L, 35L, 50mm 1.8 I, 100mm 2.8L Macro, 10-22mm EF-S, 28-135 EF, 400mm 5.6L; Nikkor 50mm 1.2 AI-S, 50mm 1.4G, 50mm 1.8D, 16mm 2.8D Fisheye, 180mm 2.8D, 100-300mm 5.6 AI-S, 18mm 2.8D, Voigtlander 90mm f/3.5 SL II