They are paying special attention to multi-touch support, for systems like the HP TouchSmart, and making many programs compatible, that were not originally created with touch-screen interface users in mind. For example, if Windows 7 knows that you are using a touch screen, it will add a little extra space between menu items in a program not made for touch-screen users. More applications will provide on-screen keyboards, recognize gestures, provide tablet-like handwriting input areas, etc.
There is a new enhanced taskbar with interactive preview thumbnails, allowing much easier navigation between open windows, and the ability to jump to a commonly used task or file with one click. From the previews I have seen, it looks pretty exciting.
Microsoft has also finally updated some of the basic tools, such as MS Paint and the MS Calculator. They have also enhanced the desktop "Gadgets" so that you have more ease-of-use and freedom in displaying only the gadgets you want open, anywhere on your desktop, instead of confined to a sidebar.
They have provided core support for media formats, including H.264 video, MJPEG, 3GP, MPEG2-TS and other common codecs. DirectX enhancments have also been made, making 3-D applications more stable and compatible than they are with Vista. HD video formats and plug-ins are also enhanced.
Microsoft is also focusing on improved networking, to make it easier to connect and sync portable devices, connect to remote networks and the Internet, and search/share data in other computers in your network. They have improved Network diagnostics tools, and Web services platforms for developers.