US Dollars are the only thing that matter when comparing the original USD price to the current USD price. The difference in price based on inflation is about $3200 today, or about $300 less than the $3500 it currently lists for.
I don't know if the OP (before edit) included exchange rate (it was there by the time I first read it earlier today) but it is relevant nevertheless. I also don't know if Canon uses the model that is being suggested but in response to your point, if you're a executive at Canon Japan, the only thing that matters is Yen and it's very reasonable to believe that Canon Japan is setting the price in Yen, converting to USD at current exchange rates, and possibly consider whether that price in USD is too high for the market. But even in the case that they did think the USD price was a bit high, I think it more likely they would set the list price as is, see what happens, and offer a behind the scenes discount to wholesalers so that the street price would go down rather than having a significant disparity in the list pricing. I know not if any of this is true or what really happens at Canon HQ... just my idle speculation.
Ok, valid points. Taking that into consideration:
Assuming an intro price of $2700 in late 2008, adjusted for inflation, that would be about $2850 today. If we account for the exchange rate, in Yen in 9/2008 (rate of about ¥106/$1) $2700 is about ¥286200...and in Yen in 3/2012 (rate of about ¥81/$1) $3500 is about ¥283500. As far as adjusting for inflation/exchange rate to the Yen is concerned, the difference in yen is about ¥2700, and in USD today that difference would be about $33.33.
As far as I can tell, Canon introduced both cameras at roughly the same price point in their own currency.
I got my exchange rates from here (really quick bing search): http://www.x-rates.com/d/JPY/USD/hist2012.html
I used the exchange rate one month prior to the intro date as list prices in the various markets are invariably preconceived, though of course they might be using different number. Either way 76 Yen:USD was used for the 5DIII and 109 for the 5DII. Inflation was 7.8%. This results in $3500 vs $4170 USD.
Canon's prices for the 5D Mark II in Japan was 300k Yen, and for the 5D Mark III is 270k Yen. The projected price should have been 320k Yen.
If you go to http://www.canon.com/camera-museum
you can see all of Canon's lenses and their intro prices in Yen. You'll notice that since the 1990's Canon has had almost no deviation in it's intro prices in Yen when adjusted for inflation. For example the 14mm f/2.8 L I was 298k yen in 1991 and 14mm f/2.8 L II was 307k yen in 2007. This matches the inflation rate down to fractions of a percent and you'll find a similar patterns in the rest of Canon's lenses and bodies, though their historical body prices aren't listed on that site.
I will agree with BobSanderson that invariably local rebates and price cuts over time will have no easily predictable pattern, as that's how Canon's pricing really works. Canon does not introduce products at what the market can bear but instead at what they have historically charged. Canon then tweaks pricing to what the market can bear with discounts. My point was simply that Canon's introduction pricing has been incredibly consistent and it is clear Canon broke tradition to price the 5DIII lower than the 5DII to begin with.