This article points out some interesting information about some new interfunctionality between live and Vista. The first thing that I thought was useful that was mentioned, was the ability to drag gadgets off of live.com and place them onto your Vista desktop. Reminds me to some degree of embedding a website into your desktop (active desktop style) but I'd expect the Vista implementation to be much more robust.
There is another mention of a gadget that will recommend TV shows. The potential here with Windows Media Center integration is where the discussed features get really interesting. Imagine being able to watch a few shows, rate them, and then get a suggestion of 10 more shows you like. Or, imagine ratining a few shows, then being able to tell your MCE "just record me the highest rated shows like this" and you will then get a nice catalog of shows that are catered to your tastes, delivered to your desktop while you're away. Then, if you have a portable media center, you will be able to synchronize, and then pick and choose from the shows you liked while you commute (if you are a bus rider like me).
I've heard a lot of speculation (externally to Microsoft) that Vista will not deliver enough exciting features to entice all users to upgrade. The closer we get to the release, the more I feel that there will be compelling features and improvements that justify the upgrade to Vista. We'll have to see how things change with the next few CTP.