We have two tags here that might qualify as "guessing game" tags - identify-this and where-on-earth. I think they're pretty popular, I like reading them, and I have asked at least one of these kinds of questions. Yet perhaps SE as a whole is going to start to lump these with "shopping questions" as the sort of stuff that is off topic site-wide.
I will say that Jeff's characterization of the "guessing game" questions as impractical gives me hope that we can keep where-on-earth at a minimum - I know my question in that tag was specifically about planning a vacation and choosing a destination.
There isn't exactly a discussion on this yet, just a "trial balloon" on the blog, but do we feel that our "guessing game" tags are not that at all, and importantly different from "what was this book I read in my teens" and the like?