Yes it has been done and gone. Austin was a test market and the plantation I worked for was the supplier for the coffee end of the concoction.
My Review of Coke Black
Taste: Not bad. Very sugary so don't expect it to taste like a shot of espresso. If you have ever had the rootbeer barrel hard candies you already know the flavor.
Coloration: Umm...its black. Really more of a Dr.Pepper color. Darker than Coke with a red tinge.
Effects: I drink ~10 shots a day at least. I go for a constant infusion of coffee bean extract throughout my waking hours. One eight ounce bottle of Coke Black made me sick to my stomache with caffine cramps. It did not keep me any more awake than a Coke does and less than coffee does.
Short recap. It sucked. Good idea but poor product.
There used to be this stuff called Zydecola. It was a chicoree cola drink from NOLA that was pretty tasty. Don't think its still around but you might want to try and search for it.
The cafeteria at my building had a coke rep one day and they were giving out free samples of this. My first impressions of it was, this is just gross....but let me try another sip....yeah...this is gross.....but let me try one more.......
it basically went like that until I had finished it. I don't think it was because I actually liked it after getting used to it but rather a function of trying to determine what it taste like.
Our cafeteria stocked it for about a month but it hasn't been seen now in over 10 months. I am assuming it was scrapped here in the Boston, MA area as well.