Well, Nikon software CAN read the D300s files right now,today. The D300s has been on the market less than one month,and Apple and Adobe are big, somewhat slow-moving companies. Adobe also wants to sell more copies of Photoshop CS--at "some point" Adobe will quit supporting certain cameras with older versions of Photoshop CS, by not updating the ACR module to encompass the newest cameras.
I'm surprised that the D300s .NEF specification is different from that of the D300. When I bought my D2x, I had to buy an entirely new version of Photoshop and/or use Nikon Capture software to convert my RAW files.
Shooting in TIFF mode would, I guess, be an option, but it's not as versatile as a 14-bit RAW NEF is....the .NEF file will always have better adjustability in terms of white balance and total DR to play with. In the meantime, you'll probably have to work harder at getting the DNG converter to install. SOftware headaches can be very annoying, so take a little bit of time, try and make sure you follow all the steps, and read the software FAQs to make sure the updates are compatible with your OS variant, etc.
Adobe has had probably only a month,or less, to get new camera updates out...this is what being on the bleeding edge of technology is like--new hardware but no new sotware form 3rd party mfrs. Right now, I would download or install the Nikon Capture free trial. Also, didn't your new Nikon also come with Nikon View NX, which has a raw converter in it?
You might also drive over to ProPhoto Supply in NW and ask for some help there. That's the only pro camera store in your entire state,and they are the only place you can probably get a straight answer in your region.