The new Xbox Live update just arrived on my Xbox 360.
The new background downloads are spiffy. Perfect for downloading those multi-hundred meg demos. Not so sure yet on the additional subdivisions of the marketplace menus. Kind of implies "more places to hunt for stuff", but it does appear there are more "New" sections which may make it easier.
Personally, I really want previews of the gamerpics and themes. I'm never gonna buy one of those things. Without a preview, it's a total crap shoot.