There are currently almost 95,000 domains in the .XXX zone file. A registration can be "defensive", in which case the name points at the ICM registry's servers and doesn't resolve, or "sponsored community", in which you make a few promises (mostly that you're an adult with a working phone number) and it's like any other domain. Some years ago Stuart Lawley, head of the registry, said they'd have rules requiring that .XXX web sites be pornographic, but that didn't happen and you're allowed to park your domain or presumably put your non-porn web site on it.

By a rough count, about 83,400 of the domains are defensive, and 14,400 are community. Of the community ones, 3200 are parked at Domain Control, and about 4000 at various other parking services so about half of the "community" domains are parked or for sale. (It may be more than that, since not all parked domains use parking service name servers.) A little spot checking of the unparked domains suggests that the majority of them either don't resolve or land at pages saying under construction or otherwise not offering the porn they're supposed to.

So at this point, the theory that .XXX will primarily be collecting money from defensive registrations of people who don't want a .XXX domain is correct. I hope ICANN is very proud that their processes worked and allowed .XXX to go live.