If u watched keynote , they said xbox one is using "Windows" kernel and showed Windows 8 Logo.
sigh...
they showed the windows "8" logo. because its the NEW windows logo. just like they changed the windows phone logo to be the same, it doesn't mean its windows 8 or not. its just the new logo that represents WINDOWS. do you think windows 9 is going to have a different logo? not really.
also lococycle is WIP, do you think only because windows 8 was released and they are subsidiary of Microsoft studios, they would automatically upgrade in the MIDDLE of the project? its a professional studio we are talking about, and honestly not professional known studio would do that ever, they wouldn't even upgrade the software (which would be "less" complicated) because that would be irresponsible for the project which has a deadline.
Edit. also the Xbox games don't even run on windows, they run on Xbox OS which is a big difference. that's why Microsoft said xbox one has 3 OS.
and some people from that article seem to forget, but this lococycle demo wasn't about xbox one, so all they wanted to show was how it looks, how it is played, what's new, etc etc. so it didn't matter where it ran, the purpose was to show only the game. and just like joenox said (thanks for your comment) developer had all the power to show the game however they wanted to the world at E3. they chose this way, it doesn't mean anything else, like not windows 8 confidence crap, or games wont run as shown in E3 keynote.