The Facebook Blog has the details on new features they've just rolled out to the main newsfeed. Interesting News, Any Time You Visit.
Users (at least in my social circle) have reacted as expected (and rightly so) and are complaining about massive changes, no opt out, and (my theory at least) that they expect this to somehow be slanted towards advertisers and not users in terms of "usability".
That all said, the new features are a "top stories" feature which keeps some stories at the top of your feed, and a (IMHO quite cool) feature that shows real time activity with Google+-like inline viewing and commenting. Probably some other stuff too, but if you're a facebook user you'll probably see a news alert in the next few hours or days depending on the rollout.
However, this is a free service that users are choosing to use, and if you really hate it that much, just leave the service and move over to .... uhm.... oh right, never mind.