The new Facebook design looks like one of the busiest interfaces I've
seen in a while. It immediately reminded me of the Yahoo! homepage
back when... well, when it was too busy. Yet somehow, the Facebook
homepage makes sense, doesn't feel too overwhelming and is easily
navigable and parse-able.
I think there are two things going on here; one is that they did a
fairly good job following basic Gestalt principles of perception to
clearly chunk out the layout and establish hierarchy.