I had not been aware of this issue, so thanks again to Mark for letting me know about it. I have confirmed this to be an issue and recommend that all photographers who process photos with Camera Raw (via Photoshop) update their workflow settings to a bit depth of 16-bits per channel and their preferred color space.
First, in Photoshop, go to the menu and choose Edit > Preferences > Camera Raw on Windows or Photoshop > Preferences > Camera Raw on Macintosh. Choose the Workflow page from the list on the left side of the Camera Raw Preferences dialog. Then, in the Color Space section toward the top of the dialog set the Depth popup to "16 Bits/Channel". Set the Space popup to your preferred color space. I generally recommend ProPhoto RGB, but the best option will depend on your overall workflow in terms of color management.
A summary of these workflow settings is shown at the bottom-center of the Camera Raw interface. I recommend that you confirm the settings are accurate within Camera Raw, and if they're not you can click on the summary text to bring up the Workflow options in the Camera Raw Preferences dialog. Note that if you had previously processed a raw capture in the 8-bit per channel bit depth that will still be the default for that image, and so you may want to re-process the image changing the bit depth to 16-bits per channel.