Up until now Microsoft hasn't given an official timeframe for the successor to Windows 7, but we've known for a while that they are targeting a 2012 release and a couple of early development milestones have already been seen in the wild. If the slides are legit I'd venture to guess that the January estimate is likely just a placeholder date, though, as it would give Microsoft little over two years to deliver what it has claimed will be their "riskiest product bet" yet.
Windows 7 took about three years to build and it was essentially an evolution of Vista. This time around the company is building two separate versions of Windows 8 for system-on-a-chip platforms from Intel and AMD on x86 architecture, as well as low power designs from the likes of Nvidia, Qualcomm, and Texas Instruments on ARM architecture.
Besides that interesting nugget the slides show a Dell tablet planned for April, dubbed "Gallo", which will be running Android 3.0 Honeycomb. Following it in June will be the "Rosemount," running Microsofts Windows 7 and featuring an HD display with a resolution of 1366 x 768. In October will come the Honeycomb-based Sterling, and what looks like an update to the Gallo with handwriting recognition.