It's been a rather speculative week when it comes to what people think the Windows 8 RTM build number will be, some say 8500, others 8600, 8800 and even 8888. The RTM is rumoured to be compiled sometime this month, so the company don't have long to make a decision.
The source thinks Windows 8 will be finalized next week with a build number of either 8600, 8800 or 8888. 8600 seems the most likely, as it would make 1000 builds since Windows 7. But 8800 and 8888 also have a good standing point, since 8800 and 8888 represent the number 8, and Microsoft seem the like that number at the moment.
It's all too early to fully understand what Microsoft is planning, we should expect a statement from Microsoft when Windows 8 hits RTM, if not I'm sure information will leak, like it always does.
source: Win8China