The next version of Windows will support multi-touch touch screens, Microsoft announced Tuesday night at the Wall Street Journal's All Things Digital Conference. The inclusion of multi-touch capabilities in Windows marks the surest sign yet that touch will join the mouse and keyboard as a common interface in computing.

"Touch-enabled surfaces are popping up everywhere, including laptop touch pads, cell phones, remote controls, GPS devices, and more," Chris Flores, a director on Microsoft's Windows client communications team, wrote in a blog post. "What becomes even more compelling is when this experience is delivered to the PC, on a wide variety of Windows notebooks, in all-in-one PC's, as well as in external monitors."

Microsoft has firmly put its stake in the ground in touch technologies already, last year announcing the tabletop Surface multi-touch computer, which is beginning to show up in AT&T stores and will soon make its public debut in places like Sheraton hotels and Harrah's casinos. Windows Vista has some single touch capabilities for tablet PCs, though those have flown largely under the radar. Microsoft also has a number of touch technologies in development at Microsoft Research. Earlier this month, Microsoft chairman Bill Gates demonstrated a multi-touch office whiteboard called TouchWall.

Microsoft's corporate VP for Windows experience program management, Julie Larson-Green, demonstrated Windows' multi-touch capabilities on a Dell Latitude tablet PC on stage at the All Things Digital conference. Microsoft also released an accompanying demonstration video that showed the capabilities being used on both a laptop and desktop PC.

Gestures like pulling fingers apart or closer together and moving fingers across the screen enlarge, shrink, rotate, or move images in a photo gallery application, play a piano in a music application, and paint a picture in a version of Microsoft Paint. Users will apparently be able to open applications with a simple touch of on-screen icons.

Another demonstration showed off a mapping application that used hand gestures to rotate a globe and zoom in and out on a map via touch gestures. That application has a ring-shaped taskbar that allows the user to, for example, switch the map from a map view to a satellite view by touching an icon, rather than clicking on one with a mouse.

Windows multi-touch apparently won't require any single touch technology. One of the technologies used in Microsoft's multi-touch demonstrations is N-Trig's DuoSense, which uses infrared sensors mounted to the front of the screen to sense touch gestures. DuoSense is already shipping on some of Dell's Latitude XT tablets and supports both pen computing with a stylus as well as multi-touch. Another supporting technology is one of the many touch-screen setups from Tyco Electronics' Elo TouchSystems.

Though it's not clear exactly what other technologies could be behind multi-touch in Windows 7, one Microsoft Research project,ThinSight, also appears similar to the Windows multi-touch Microsoft demonstrated at All Things Digital. ThinSight uses off-the-shelf infrared sensors mounted inside the display to detect fingertips or other objects on or near even a thin LCD monitor such as is found in a laptop. ThinSight could allow users to point an infrared device like a remote control at a screen to interact with Windows as well.

The unveiling of multi-touch features in Windows 7 is part of an orchestrated effort this week to begin detailing the upcoming operating system, which is due in late 2009 or early 2010. Also on Tuesday, Microsoft announced that Windows 7 would support the same devices and applications supported by Windows Vista and run under the same hardware requirements.

On Wednesday morning, Microsoft opened registration for its Professional Developers Conference in October, and began laying out the agenda for the conference. Windows 7 appears to play a significant role, and the preliminary agenda details some other new features of the new operating system.

For example, improvements to DirectX will add increased support for high-end graphics, a new networking API will allow developers to build "SOAP-based Web services in native code," a touch API will allow developers to take advantage of Windows 7's touch and gesture support, and there will be new energy-efficiency features.