Facebook launched a new version of "Groups" -- a simple way to stay up to date with small groups of your friends and to share things with only them in a private space. From this space, you can quickly post photos, make plans and keep up with ongoing conversations, everyone in the group will receive a notification about it. Also added a bunch of new features to Groups to make sharing and communication with small groups of people easier.
You can also group chat with members who're online right now. You can even use each group as an email list to quickly share things when you're not on Facebook. The net effect is your whole experience is organized around spaces of the people you care most about.
By default, Groups are Closed, meaning anything posted is only visible to people in it. The name of the group and its members are visible for everyone to find the right group. You can also use settings to create "Secret" groups, or create "Open" public groups.
Groups gets a home in main navigational area. Bookmarks and Groups will both appear above the fold and follow same conventions in that they only appear as long as user remains engaged.
Also enhanced Graph API to support this new functionality.