Facebook's Graph Search has been updated to allow people to search in greater depth on Facebook. The new Graph Search now allows users to search for not just the usual people and places, but also to search posts, status updates, check-ins, and comments on Facebook.
Yet users also now allows you to search within a period of time, such as posts within the last month or year:
You can also search for comments made by people posting from a specific location. Users can also search specifically for posts that they have commented then and search their own posts, and narrow those searches within a specific time period.
Facebook's privacy settings do apply to the newly added search features in Graph Search. This means that you can search for things posted by people you are friends with, as well as things been posted publicly. However, if you aren't friends with someone, you can't search for their posts and comments unless they are shared publicly.
This is rolling out in groups so not everyone will be able to use the new features yet.
If you're already part of Graph Search, and you're unsure whether you have received the new features, simply type into your Facebook search box "posts about _____" with anything you know your friends of posted about. If it isn't available on your account yet, it will say "Post search is not yet supported"; however if your graph search has been updated, you will see the search results for it.
If you haven't signed up for a Graph Search yet, English users in the U.S. can sign up here.