It seems every gear maker is rolling out grey in some flavor or another. However, greys seem to vary greatly across manufacturers and there is no real standard for what Urban Grey should look like. Some manufacturers even seem to be offering rebranded Foliage Green!
Enter the Monkey. Mil-Spec Monkey recently posted a very interesting look at how to build a better Urban Grey. He seeks to find a neutral color that splits the difference between the warm and cool greys often found in an urban environment. It will be interesting to see if any manufacturers can act on what the Monkey found.
I should also note that this article and series of images will give you a new appreciation for the versatility Tan499.
Urban Gray actually has a Pantone Color per Natick, Urban Gray 501/505, as it is a component of the Universal Camo Pattern. ITW used to manufacture GhillieTex parts in this color as well.