There’s not much here yet, but GBM reader Jason Horrocks points us to this Channel 9 link that talks about pen and touch input. Here’s a quote:
Metro style apps are much better with ink! In Windows 8, you code your Metro style apps for touch, and get pen and mouse support for free. In addition, with the new Windows 8 API for ink, you can expand your app’s capability and support ink strokes with precise control over Pen width and color.
You can check out the rest here.
You may have also seen this video from WinRumors showing off pen and touch in Win 8.