It isn't a secret that Microsoft is working on the successor to Windows 7, but the progress so far has remained a secret.
Windows 8, the codename for the next major operating system from Microsoft, has already passed Milestone 2 progress. According to a Russian website winreview.ru, via win8beta.com, Microsoft compiled the build "Windows 8 Milestone 2: 6.2.79xx.0.winmain_win8m2.xxxxxx-xxxx" recently.
The compiled build news comes just days before CES 2011, meaning Microsoft might have a sneak preview for a select few, but the chances are very unlikely. The emerging details mean that Microsoft is already working on Milestone 3, which is expected to be completed by the end of February 2011.