I covered the initial changes (the Ticker and Top News feed) Facebook already leaked in yesterday's post, but the most noteworthy announcement from yesterday was the Timeline feature.
The Timeline will eventually replace the current profile page, and is both a visual and conceptual overhaul.
The idea is that the Timeline would curate all of your past Facebook activity into a scrapbook of the most important moments. It's still in developer mode and not open to the public yet, but I took a screenshot of my profile so you can see what it would be like:
As you can see, the profile picture setup has changed. Instead of the 180x540 pixel size, you now have the square thumbnail picture and the giant Cover Photo. Also, the two column approach to the main section is also a big departure from the old profile setup.
Visually, there is a lot more real estate to work with, which is great news for designers and the artistically-inclined. It'll be a while until these new changes go into affect for everyone, but it'll be a dramatic change for the 800 million Facebook users.