I have a theory that big interactive pieces like that are Googleesque 20% time for the journalists and/or interactive folks that work there. I can't speak for the Times because, as another comment points out, they stand alone in journalism; however, every outfit I've ever worked at did not have enough hours in a day to pull off pieces like that with the workforce at employ.
There's at least one person from the digital side of the Times that contributes to Hacker News, the person that wrote the fantastic Emphasis[1]. (I've been looking for a chance to use it.) Wonder if he'll -- forgive the ambiguity, I've forgotten his username -- show up in this thread and shed some light on our speculation.
EDIT: Ah, he's left the NYT[2].