you have to compare it with the Canon 1Ds Mark III. The Sony Alpha A900 is the Pro model of Sony. It has 24MP.
The new Canon 5D Mark II was announced AFTER the Sony A900 and you can bet on the fact, that Canon originally wanted to ask for a higher price than 2700 USD for the 5D Mk II. This is only a reaction on the Sony A900 price announcement.
So the price war is already going on. I.e. prices for the Nikon D700 dropped already significantly in Germany last week
Can't compare A900 with 1Ds Mk III. It is not in the same league. Even Sony did not claim this as a pro model. They said this is for amateur and enthusiasts. Can't find the article from Sony when this was announced.
It is really good to see these cameras are now within reach of lots of people.