According to a report in Business Insider, Microsoft will publicly demonstrate Windows 8 for Tablet PCs for the first time by the end of June. The software giant previously showed off a very early version of Windows 8 running on ARM hardware, but that version of the software looked and behaved identically to its predecessor, Windows 7.
The report notes that Microsoft is utilizing an "Apple-like" design for the interface, which will also use elements of the "Metro" UI from Windows Phone 7. This corresponds to information I've received from sources at Microsoft, which I exclusively published in an article on the SuperSite for Windows back in early January. In that article, I noted that Microsoft was developing a new tile-based UI (code-named Mosh) that could appear as the default UI on low-end tablet-like devices aimed at the iPad.
According to my sources, the Windows 8 development schedule will closely mirror that of Windows 7, so it's not hard to extrapolate a rough timeline, with a first private beta of the release expected by September or October at the latest (most likely at a Professional Developers Conference—PDC), a private beta by the end of 2011, and the final release by mid-2012.
Indeed, this schedule has been all but confirmed by a separate report from ZD's Mary Jo Foley, who noted recently that Windows 8 had recently passed the so-called M2 (for "milestone 2") release and was heading toward M3, which will be the milestone build used in Business Insider's reported tablet demo. Foley notes that the schedule has Windows 8 pointed toward a mid-2012 release, as well.
Although information about Windows 8 is currently spotty, I've also been told that this next OS will feature a new application model, code-named Jupiter and using a Silverlight-based development model that's similar to that used by Windows Phone. Sources have separately told me that Windows 8 will be used for the basis of Windows Phone 8, where both OS lines are consolidated into a single family of products.