I’m a little late on this one:

NY Times article with Sanborn

WIRED article from Kim
Not in a million years would I have predicted he would give an out-and-out clue.  NYPVTT is BERLIN in K4.

From the sounds of it, he’s so done with dealing with this that he just wants it finished.  The fact that he set up a website to enable solving checks suggests to me that he thinks “BERLIN” is a big enough clue to enable someone to solve it in under a year but not so easy that it will invalidate the challenge of it.

So let’s all thank the crazy bitch who showed up in his front yard.  Without her and the many others driving him insane, this cipher may have gone unsolved.  And for that, we thank you.  I think.

To the cipher!