Well, they don't usually give us much warning on these things, so at 4:44 PM PDT we received word that the PTRs were going offline for patch maintenance with no ETA on them coming back online. The fact that the PTRs continue to be updated, despite being online since July 17th, makes me feel that patch 1.12 is still something that's being fine tuned - which lends me to think that the patch going live may still be some time off. Of course... Blizzard has been known to surprise me before, so take this thought with a grain of salt (or two or three). And... since the test realms are still online and going strong - it's a great place to have some fun playing a class you know nothing about!
Update: The PTRs seem to have come back online at 7:25 PM PDT.