I've been wondering about this for a while. This one shows up ranked fairly highly on Google searches for alloy. I was very confused but I suspect it's an identically or confusingly named fork. But when I first discovered it, I spent a while assuming that development had just migrated to GitHub.
In any case if it has, in my personal opinion it's quite shady to fork a project and remove all reference to the pre-fork, except the cover of the book, which is just a picture and not even a link to the original MIT site.
Has the original alloy gone unmaintained?