I think that Canon with the introduction of the 5D filled a gap in the market, which was a "reasonably priced" full frame camera. My view is that it was made with a view to compete with the now-discontinued Kodak full frame.. which was retailing for $2500 before all the stock ran out. Canon always prices a premium into new releases, and generally lowers the price by around 10% once a suitable volume of sales has been reached, or a certain time period has elapsed. So the first $300 dicount can be explained that way. The second "rebate" though indicates to me that it is having a tougher time selling, probably due to the much cheaper D200 being available. The RAW survey:
http://www.openraw.org/2006rawsurvey/chapter1notes that more than a third of their respondants were Nikon shooters. As most of these are pros or serious hobbyists, it's exactly the target market for both the D200 and 5D are aimed at.
In my book that means that Canon is having to fight with a "supposedly" inferior camera, although even as a Canon shooter I can vouch for the fact that the D200 is a quality machine, and "even" with a reduced frame sensor is capable of some pretty starling results. Add to that the raft of features included (fast frame rate, intervalometer, pop up flash, good battery life, weather sealed) in some ways turns it into a better camera than the 5D. I own a 5D and play with a friend's D200, so I am able to compare both. I am honest enough with myself to understand that the D200 is SERIOUS competition. And that in my books is good.. forcing Canon to price the 5D more realistically, seeing as they have skimped on quality or pro features and must now make amends by lowering price.
Add to all this the fact that Photokina, which is traditionally more important than the annual PMA, is now looming.. and you have the recipe for some interesting new cameras, at least from Canon. For us 5D owners, I just hope that whatever is coming doesn't make me bite my nails at having chosen the 5D!