From the GamerscoreBlog, by Sarah Nicholson;

“Ahhh
Themes – There’s been a lot of chatter about whether or not you can
keep what you have, how they will look and how the new stuff will be
different. We’ll be tackling all of that today so pay attention! Also
in this week’s Developer Diaries, we’re going to show you more on the
new Friends Channel – another area we got a lot of questions about
after we first showed it to you at E3.

This fall, themes are getting even more detailed with the New
Xbox Experience. Themes will take over more than just the background of
your Dashboard – they will be present on every channel in cool, dynamic
ways. Yes, I said, “DYNAMIC.” Check out the screens below that show the
Underground Theme on the Dashboard and the Friends Channel. (Remember,
to see the images more clearly, click on them and you will be sent to
our flickr feed.)

Every graphic on each channel will tie into your theme and
change if you choose a different one. You can really see this on the
Friends Channel – each of your friends’ Avatars will stand next to a
different graphic or environment. These graphics will match the theme
you choose and will change dynamically as you navigate from channel to
channel. But that’s not all; the themes will be subtly animated. This
is some pretty cool stuff when you see it.

This is what your Dashboard and Friends Channel would look
like with the Signature Theme – picture the bubbles in the background
moving, shrinking, growing – you get the idea.

Also on the Friends Channel, you’ll be able to see your friends’
Avatars rally when you host a LIVE party. You can see who is online and
offline by what their Avatars are doing, too. Online? Your friends will
emote and be able to wave you over to jump into their party. Offline?
Well, they’re snoozing, of course.

Finally (and many of you have asked us about this) don’t worry –
you can still use the themes you previously purchased with the New Xbox
Experience. They’ll look even better over the new UI, especially in
high-definition. Below is what a current “Gears of War” theme would
look like:

That’s it for this week’s Developer Diaries. We hope you like
what you’ve seen so far, and check back next week for more details on
the New Xbox Experience.”