Microsoft sure likes to cover its bases and leave the gaming community wondering just what it has planned. Back in March, some Xbox FL domains were registered and now some other Xbox domains have passed into its ownership. Microsoft has won some disputes against a Chinese resident over various Xbox domains and now owns Xbox8.us, Xbox8.org, and even some for Xbox Live TV, Xbox Phone, and Xbox Tablet. Those last three are understandable to secure rights to, especially Xbox Live TV, but it is the Xbox 8 ones that raise the eyebrow. Microsoft has brought the Metro UI to the current Xbox 360, and with Windows 8 and Windows Phone 8 both making use of that UI, an Xbox 8 would follow the same naming scheme. It would also throw conventional naming schemes out of whack, since we would go from Xbox to Xbox 360 to Xbox 8, but hey, maybe Microsoft wants to make a statement about the unified Windows 8 landscape.
There are other Xbox domains currently registered that Microsoft is engaged in disputes with, but no complaint has been filed against the owner of Xbox8.com (another Chinese resident). This could all just be Microsoft wanting to own every domain related to Xbox, but we just have to see where this Xbox 8 stuff goes.