This dealer is just trying to get rid of last year's inventory. Unfortunately, a lot of people are going to accept this as gospel. To quote part of the old saying, "You can fool some of the people all of the time".
At least at Freightliner, they're working to hold down any price increase due to the added electronics and emissions to 4K per truck. That's not too bad when you consider that a Class 8 semi costs an average of 150K out the door. That's from Freightliner, if you're talking Volvo, Mack, Peterbilt, the price is even higher (if I can believe the managers I work for

)
Even with that info available, there's still all sorts of wild rumors floating around the plant as to what the '07 trucks will end up costing.
IMHO, there is one valid reason for getting an '06 while you can - the ability to run other than ULSD. While 80% of the on-road diesel sold by mid-October is supposed to be ULSD, the drop dead date for it ALL being ULSD isn't until 2010. There's still the possibility on a long trip out in the boonies that you'd get stuck someplace with only LSD available, because that particular station didn't do enough business selling diesel to bother switching over until they were required to.