With the Windows 8 Developer Preview, it has become clear that Microsoft wants one OS for tablets and desktops. Based on my experience using the Windows 8 Preview, traditional desktop apps really felt like they were given short shrift, and the touch metaphors for tablets did not translate well to the keyboard/mouse combination.
While it is a tough call to decide if you should develop Metro/WinRT apps or “legacy” applications moving forwards, Metro/WinRT does give us the opportunity to develop one application to span multiple devices. (Take the poll: Will you write Web, legacy, or Metro apps for Windows 8?) And if Microsoft decides to make Windows 8 its phone and game console OS, the market gets even wider.