We hope you weren’t planning any all night Halo 3 fests for tonight, or needed to download any new music tomorrow, because in just a little over 4 short hours, both Xbox Live and Zune online services will be offline for possibly as long as two days.
Larry Hryb (AKA Major Nelson) earlier this week announced on his website that Microsoft will be taking the Xbox Live service offline starting at 12:01 AM PST and that it will be down for possibly 24 hours. In addition, Cesar Menendez announced over at Zune Insider that, beginning at the same time, Zune services will be down for possibly 48 hours.
Hryb and Mendendez have outlined that during this service disruption the following services will be offline. Xbox LIVE, the ‘My Xbox’ section of Xbox.com, Zune Social, the Zune Marketplace and both the Zune.net forums and the Xbox.com forums will be in read only mode.
While Hryb acknowledged that this maintenance window is in preparation for the new Xbox experience, it will not include that update or any other new features for users of either service. The Xbox Live and Zune’s online services are interconnected in many areas including some contact list & profile sharing as well as the "Microsoft Points" currency system.
The new Xbox Live experience is expected to be available later this fall. Is it possible that both systems will be down to further connect the two and that when the new experience is finally rolled out that Zune will take center stage on the platform?

Source- Neowin