This is going to get very exciting in the coming months. This is all about cross sell opportunities and integration to drive you to those products. Look at what adding Netflix did. Xbox live has driven over one million users to Netflix online. In return, Netflix is using those traffic numbers to convince studios to allow them to release more streaming content.
Zune HD could be huge for both Zune and Xbox. All MS has to do is get a fraction of it's 20 million users to go and buy one. If MS is smart they will give discounts to XBOX Live gold members to convince them to pick one up.
The only thing that would be missing is a unified store front for Music, movies and Applications (like the Itunes Store) for Zune HD users that don't have XBOX LIVE. The rest of us who do have live can either use the Microsoft store or simpley plug in a Zune HD and use the Xbox Live interface. The best of both worlds.
Microsoft is working on that too.
Windows App Store
http://news.cnet.com/8301-13860_3-10193205-56.html
I think it will be huge if you can buy all your music, video and application for your Zune HD (and Windows Mobile enable Cell phones) all in one place. Much like Apples IPhone, you better believe that games on the Zune HD and Windows Mobile platforms will be a big part of the push.
The icing on the cake will be the Microsoft Retail stores that will push their integrated products that will compete with the Apple Stores.
http://www.neowin.net/news/main/09/07/16/microsoft-stores-to-open-beside-apple-stores
I love this mainly becuase competition is good in the market place and Apple has been by far the dominate player in music players and online music sales.