Last week, Facebook added a feature that allowed users to ignore friend requests without rejecting them. It seems, though, that it also acts like Twitter's "follow" feature—the requesting user sees the requested user's statuses, but not the other way around.
In a strangely unpublicised move, Facebook has replaced the "Ignore" button with a "Not Now" button in friend requests. This button moves those requests to a state of limbo, in which you can come back to them later and accept or block the user. The ignored user will not be notified, and they can't send you another request while it's in this pending state.
The interesting part is, in its never-ending quest to become Twitter, apparently Facebook has secretly added some extra functionality to this new feature. When pressed, the requesting user does not show up in the requested user's timeline. However, as long as the requested user's status updates are public (or otherwise viewable to the requesting user), their updates will show up in the requesting user's News Feed. We're not sure how well it will actually work as a "follow" feature—especially if most people don't know that this is how it work—but it is there. So, if someone keeps trying to friend you (or if you don't mind being in their News Feed as long as they're not in yours), the Not Now button is a nice addition to the site.