I've used this analogy before...
It would be as if ford never made any cars between the Model T and the new Mustang than said that they were better than GM because this years Corvette isn't as much of an improvement over the model they made 5 years ago.
It's a fact that the PS3 is more of an improvement over the PS2 than the Xbox360 is over the Xbox. That doesn't mean they both arn't HUGE steps.
The PS3 is estimated to be be about 25 times more powerful than the PS2 while the Xbox360 is estimated to be about 14 times more powerful than the Xbox. To give you and example the PS2 was about 10 times more powerful than the PS1...
Based on the difference in performance between the PS2 and Xbox the power increases they'll both be getting will put them on equal playing fields next generation.
So the only reason Xbox360 would look like xbox1.5 to Sony is because they've been working with such stanky old shit for so long... it really does look like 1.5 by comparison
