Why does it work in iPhoto'08 and not Aperture 1.5.x?
If it's true that in order to use Nikon D3/D300 RAW files in Aperture, we are forced to buy Aperture 2,then Apple is playing a kind of extortion game. It's unconscionable that they would allow the Finder, iPhoto '08, and Preview to recognize and work with D3/D300 RAW and purposely not permit the existing version of Aperture to read those same files.
So instead of allowing the existing version of Aperture to read it, which it should be able to because the less sophisticated iPhoto can, Apple is forcing Aperture users to pay the $99 upgrade price. This is just insult upon injury. Not only did we have to wait three months for OS X to recognize D3/D300 files, but now that OS X can read those files natively, for some reason the current Aperture was not modified to do so and thus we are being coerced into upgrading to Aperture 2.
This is dirty pool and it is something that I truly did not expect from Apple. I have been an advocate of theirs since the first Macintosh came out in 1984. Never would I have thought that they would do something like this. This is a low and petty move unbecoming of a company like Apple.