This summer saw the release of two great, innovative products. One launched with a media blitz that rivals anything the industry has ever seen: Apple's iPhone. The other--less well known but just as innovative--was Microsoft's Surface. Neither may look much like your old desktop PC, but both are just computers. The important difference is that these are computers you're really going to want to touch.

Both the iPhone and Microsoft Surface use touch-sensitive screens as a primary interface. Instead of employing a mouse, stylus, or keyboard, you use just your finger and the screen. It may seem like a small thing, but it is the most important concept to hit computing since the modest mouse.

Touch screens have been with us for some time. The first touch sensor, released in 1971, was developed by Sam Hurst, Ph.D., an instructor at the University of Kentucky. This original sensor wasn't transparent, but it laid the foundations for the touch screens used everywhere from your Treo to the ATM machine on the corner. All these are just simple, single-touch screens. The world got an idea of what multitouch screens could do when Jeff Han, a researcher at the NYU Courant Institute of Mathematical Sciences, demoed one before a crowd of technorati in 2006. Han demonstrated a funky interactive lava light application, a digital light box that let him resize images just by grabbing the sides with his fingers, and even a Google Earth-like app that let him spin around the world with just his fingertips. The presentation drew rounds of applause, and the video quickly became all the rage on YouTube.

Han has since formed a company, Perceptive Pixel, to commercialize his multitouch technology, and you can check out its Web site to see the latest work. In fact, a lot of the functionality Han demoed is now shipping in Microsoft Surface. Microsoft assured me that the company developed its technology independently, but the similarities almost demand some kind of patent wrangling.

After watching Han's demo, I thought that touch screens were cool. But it was actually using the Microsoft Surface computer that really won me over. It looks a lot like a coffee table, but you won't want to put your feet up on it. Images are projected onto the display via a custom DLP engine. Five infrared cameras set below the display detect contact with the display and let you navigate the interface. The flat display measures 30 inches diagonally and is designed to make it easy for multiple users to touch.

The first application I tried was a simple paint program. I painted on the screen using my fingertips and a basic palette of colors and effects. I was also able to manipulate photos--moving them around the screen, making them larger or smaller, even e-mailing them, just with my fingers.

Surface computing isn't only for playing around. The system supports object recognition using a technology, dubbed Domino, which works like a bar code. A Domino tag--basically a small sticker with a black-and-white pattern--allows the Surface computer to recognize another electronic device instantly. In our demo, a Wi-Fi digital camera was placed on the surface, and its contents were instantly displayed as a pile of snapshots. From there, they could be moved around the screen, resized, or sent to other users via e-mail. Granted, it was a controlled demo, but the pairing was wireless and completely intuitive. The interface had disappeared.

Unfortunately, you and I can't buy Microsoft's Surface computer; it's available only to corporate clients such as Harrah's Casinos and T-Mobile. You can buy the iPhone, but that's a pretty pricey purchase. The lack of a real keyboard is probably my biggest problem with the iPhone, aside from its being locked to AT&T as a carrier. Still, the touch screen is perfect for tapping through a smartphone's dozens of options and screens.

New interfaces never completely replace the old ones--they just supplement them. Most navigation is done using a mouse. Nonetheless, there are times when a keyboard comes in darn handy. You need both to get the most from your personal computer. Pretty soon, you'll need a touch screen as well.