Yes, I am digging and looking for any information that will confirm exactly what this is.... a board game or a full on tabletop mini's game release. The latest information I have though is not yet definitive, and exactly as I get the info.... I will be on it and let you know what we are looking at.
Here are the latest rumors, these ones come from Dakka
via krazynadechukr
BTW, my source "confirmed" it will be $149.99 USD (he is so certain he said if it is more, he will pay the difference for me. I have witnesses to his saying that, and I am holding him to it.)
via judgedoug
From my source: This is a big release. GW reps are getting two days of training on the product line and rules, as they did with Age of Sigmar.
My opinion: This implies it will be the launch of a whole separate product line, and not just an accessory to 40k.