Microsoft’s Windows 8 develop schedule will include one beta and one RC before the RTM and general availability points.

Windows chief Steven Sinofsky revealed the schedule in a keynote address on Tuesday. The schedule is identical to Microsoft’s Windows 7 development plan. Microsoft didn’t hint when the beta would be made available but Sinofsky said the team is focussed on quality rather than dates. Microsoft is generally expected to announce a beta at CES 2012, the same schedule as Windows 7 followed.
Windows 8 beta and RC on the horizon, updates to developer build | WinRumors