The Windows Touch Team has posted a very in depth report on the new touch capabilities on the Windows 7 Engineering blog...
Making Windows Touchable
With Windows 7 we have enriched the Windows experience with touch, making touch a first-class way to interact with your PC alongside the mouse and keyboard. We focused on common activities and refined them thoughtfully with touch in mind. You will have the freedom of direct interaction, like being able to reach out and slowly scroll a web page then flick quickly to move through it. With new touch optimized applications from creative software developers you will be able to immerse yourself as you explore you photos, browse the globe, or go after bad guys in your favorite games.
Windows 7 has a simple set of touch gestures that work in many existing applications. These include the basics of tap and drag, as well as scroll, right-click, back, forward, zoom, and rotate. More details on how gestures work is described later.
Improved high DPI support:
Windows 7 has improved high dpi support (see High DPI blog post).
Improved window management:
The updated taskbar and windows arranging features go a long way towards making Windows easier to use with touch.
o The taskbar buttons and thumbnails are ideally sized for pressing with touch, and specific behaviors are tuned for touch input.
o Aero Peek has been tuned to work with touch
o Sizing and positioning windows is easy with Aero Snap
Refinements to key experiences:
The top browsing and media activities were refined to provide an optimized touch experience. IE8 includes support for the core touch gestures (scrolling, back, forward, zoom) as well as an optimized address bar that opens by dragging down, and extra spacing in favorites and history lists when opened with touch for easy selection. In Windows Media Player, the transport controls (play, pause, etc) have larger clickable areas even though they still look the same size - so that they are easier to touch.
The on-screen keyboard has been optimized for touch with glow key feedback that's visible when your finger is covering the letter and multitouch support for natural typing behavior and key combinations. It's designed for quick usage, like entering a URL.