According to Bloomberg, Microsoft is planning general availability of Windows 8 and devices running it in October. An October launch would still be in time for the holiday shopping season.
Bloomberg says that Microsoft will hold an event for partners in April to provide more details on launch timing and marketing strategy.
As reported elsewhere, the story says that "fewer than five" ARM-based Windows devices will be available at the time and there will be more than 40 Intel-based devices. Bloomberg cites "people with knowledge of the schedule" as saying that the ARM device shortage is "...because Microsoft has tightly controlled the number and set rigorous quality-control standards."
A pre-beta version of Windows 8 running on a tablet.