These are XML syndication feeds which list new topics that the New York Times assigns to its articles. The feeds are updated on a daily basis.
"New" just means that I had to create a new root level directory in http://aaronland.info/nytimes/knows so you shouldn't read too much into the date that a topic was added.
A note to the paranoid and otherwise bored : All your RSS feeds are not belong to me. Once this one has shaken out a bit and I see how it's going to work, I will add flavours other than Atom . I just wanted an excuse to try XML::Atom .
Meanwhile, I will be in the other room patiently waiting for the New York Times to offer me a job.