Speculation about Windows8 is largely built from short interviews from Microsoft employees. There have been interviews with Robert Morgan and Anders Vindberg of Microsoft. They say little but give some hints about what is to come.
Will Windows 8 be released in 2012 or 2011? Will it be 128 bit, or 64 bit? Will it be the end of the 32 bit OS, like XP. Will Midori be distributed, or will it be the beginning of a cloud?
The user interface, is probably going to be a big part of the next change in the OS. Consider how much Windows7 was designed to look like the Mac interface, with its jump lists, and taskbar modification and the like.