1. They want to link the Xbox range with Windows 8 and infinity looks like at 8 on its side.
2. It fits with the branding idea of offering 'unlimited' entertainment. They've already used this to describe the 360 so they're obviously thinking about it.
3. It has been seen on development kit software.
4. It is two circles (360) put together. It looks like the Xbox 720.
5. They are likely to offer cloud gaming at some point, which effectively makes the Xbox Infinity an infinitely extensible system.
6. It is an easy brand to flash on advertisements. They can hype it to infinity.
7. Noone else is using the symbol. It represents infinite possibilities, I.E. Apps as well as games and music and video.
8. The system seems to be using groups of 8 as it's design target if the rumours are true. 64MB of embedded RAM, 8 cores and 8 Gigabytes of RAM are rumoured as specs and each are divisible by 8.
Tease.
