Support for raw files on the Mac is built into the OS, and that is what Apple applications rely on. (Lightroom and Photoshop use Camera Raw and do not rely on OSX for raw conversion.)
Built-in OS raw file support is handy in many ways, for example, even basic applications such as iPhoto and Preview can open raw files, but it means that support for new raw file formats only comes with OS upgrades. It also means that to have ongoing support for new cameras, a user must stay up to date with OS upgrades. You will probably see support for the D300 in release 10.5.2 of the OS which is rumoured to be immanent. It is unlikely that there will be an upgrade to Tiger (OS 10.4) to support new raw files.
The current raw file support status is at:
Our Nikon friends are not alone with this problem it also applies to a number of other quite important cameras.
I recently went to the Aperture Users' Professional Network (on the basis that with a name like that it might have some influence with the appropriate Product Managers at Apple) to complain that my G9, Sony A700 (so as to use years of accumulated Minolta glass), and 1DsIII were not supported and pointing out that Adobe supported each of them BEFORE public release.
I was initially greeted by an intemperate rant that one should not buy a new model until Apple were prepared to support it which they would do when they were good and ready ! - and in any case nobody really needed RAW as he made his living without it !!!
Subsequent and rather more polite, intelligent and better informed responses took the line of 'explaining' the problem of Apple's architecture needing a major OS update to enable new support.
The first response does not deserve to be dignified by a resonse.
However the second rather misses the point in my view. Even Apple with all their success and advantages needs to acknowledge the real - and competitive - world and if necessary adjust to it.
Do I remember a business adage that being second means you need to try harder? And whatever the position of other Apple products Aperture, whilst it may be best in some minds, is definitely not first in its specific market.
However much we love many of their products and offerings sentiment has its limits - even if one crosses them reluctantly!
With such reluctance I have just bought Lightroom- and a couple of lightroom instructional books.
I have no wish whatsoever to spend more time with the computer learning an 'ambidextrous' workflow but for a time I will have to do that - but how long until frustration and practicality lead to changing over to a single non-Aperture system ?
I know that in myself I am totally insignificant in calculations at Apple - but I wonder how many others have similar feelings and how loudly they are prepared to voice them? Because I am sure that the best way not to get any change is to say nothing and just wait patiently - I am also certain that does not serve well the best long term interests of Apple itself.