It updates the Yahoo Widgets mainframe so that new features can be used. RallyPoint, for instance, allows you to bring up the widget while watching TV in the background, whereas before it only allowed you to watch with the picture to the side.
I'm working to get update information posted, but it's been a slow process. I appreciate your patience in advance.
There is a firmware posted on Sep 22, 2009 for the 7000 series. I'm wondering if anyone has any info as to what exact changes/updates are included with this version.