For example, this is how the "News" and "Sport" sections looked when I first visited the page:
Then, I clicked into the "News" section and repeated this process a few times, to "teach" it that I visit the News section often. When I went back to the home page, "News" was given a darker background color, giving it more prominence:
This is an outstanding idea -- and one I could see being applied to font sizes and positioning, as well. Kudos to the BBC for proving again it is an industry leader in adapting new technologies into its news and information sites (such as RSS feeds and accessibility measures).
I do see one problem, though, with the BBC's implementation of the dynamic background-color changes. Simply put, the home page, by default, already uses quite a few different background colors. So it's hard to tell whether the background color for a particular section is in a darker shade of blue because of personalization, or because of the site designers' judgment. Granted, they're probably still experimenting with this feature, but if they're serious about it, they should make all default background colors the same.