I suspect it's because it wasn't as well publicized on BGG. There was a comment from a user earlier today in the thread announcing the original puzzle.

I wouldn't have noticed at all if I didn't subscribe to updates to Stonehenge on BGG. There was nothing in your feed (http://paizo.com/titanicGames&xml=atom), and I sure as heck don't have the time to go check publisher sites manually every day.

Haven't had a chance to look at the puzzle yet, other than a cursory glance. I'm currently assuming it's some sort of cipher, but as I said, no chance to actually look at it.

Hah, got it. You really don't need to read about Stonehenge on Wikipedia. Just one hint: You don't need to click on things, just mouseover them. You can tell this by looking at the file source; it has nothing to do with the solution.

No real hints from me - I'll leave that to the admins.

I will say that I expect the, ah, result to be interesting in the coming months.

One thing that still baffles me: why are there two different "You have not found the key" pages?