A new entry appeared - now users have RSS feeds, each RSS feed has multiple entries, and a list of subscribers. What’s surprising is that the code mentions RSS specifically, and distinctly from existing interest lists and friend lists. Also, note that this is unconnected to Facebook outputting RSS feeds, which they’ve done for a while.
I have looked over it myself, and while it's not clear how Facebook plans to use the new code I do tend to agree with Tom. The way the code is structured suggests to me that Facebook is going to let each user subscribe to RSS feeds and read the content inside Facebook.
I would also bet that this has nothing to do with any internal uses of Facebook; while they do have streams of content (you can follow people and subscribe to pages via RSS feeds) so far as I know those are described elsewhere. No, this is something new.
So Facebook is getting into the news reader business.
Actually, I would like to disabuse you of the phrase "getting into". Facebook is already a source of news for many of its members, both for what other members are doing and for what is happening in the world. Depending on how you frame the argument Facebook has been the largest news reader since at least 2010, though much of that involved linking to stories that were actually read elsewhere.
This new development would be better described as bringing more order to the news reading, gathering, and sharing. And I would bet that this is also a sign that Facebook wants to keep those news junkies inside Facebook's own walled garden (where Facebook can throw more adds at them).
It's not clear yet how this will affect other news reader apps, but there is a good chance that Facebook will grab a sizable chunk of the market. Facebook reported having 483 million daily users when the company went public last year, and if only 10% of that number switch from their current news reader app to Facebook then this service will immediately become one of the largest news reader services.
The only service that would be larger would be Flipboard, which reportedly currently has around 56 million users.
I'm not just name-dropping here; Flipboard is worth mentioning because I would bet that Facebook is going to offer a magazine-style news reader app as well as a more dense app like Feedly, CommaFeed, etc. If nothing else they would be fools not to support all types of users.
But unfortunately at this point all I have is speculation. I have queried Facebook for confirmation, and I will post their response when it arrives.