A new navel orange variety
http://www.pacificfresh.com.au/index.php?option=com_content&view=article&id=47&Itemid=37
also tv program has a bit of video near the end
http://www.abc.net.au/landline/content/2013/s3843593.htm

Very informative video.
The brown skin navel looks to be more brown/green to me. It will certainly be interesting to see if consumers will be interested in it.

Will be a hard sell to shoppers as the fruit has an unripe even spoiled look. Many shoppers go through fruit hand picking out only the freshest best looking fruit now. A brown fruit would be passed over quickly, and left behind, as it dosen't look very appetizing.. - Millet

Why does one have orange fruit and the other brown. Could it be infested with rust mites?

I think it is a genuine brown skin, as far as I know brown capsicum and chili and also brown tomato types develop red pigments, and continue to retain chlorophyll (green), so the combination causes brown colour to appear.
Something similar going on here ?