The default is to show what your friends have posted, uploaded pics, changed avatars, started new forum topics, posted to groups, etc. This assumes you have made some friends (in software terms) and are following them. But at the top of the feed, there is a tab control that looks like this:
Click the "View all" and wait a second. Ideally it would have a little animation to show you it's loading but it doesn't (yet.) Suddenly, you'll see a bunch more activity in this list from everyone on the site. If they've kept their privacy settings open, you can see their new avatar or pics uploaded, etc. It makes for kind of a different but very useful experience in surfing the community's activity and content.
So while most use the forum, keep in mind there's more community content to check out by just unfiltering your Feed. If you don't use it or don't care, that's fine too. One nice feature about it is that you can post to your "Wall" and share things with only your friends.
