Social play doesn't mean just playing with other kids -- the toys are now talking among themselves. At Lego, designers put a microchip and an infrared transmitter in a box with some Lego bricks, called it Lego Mindstorms and turned it loose. Kids (O.K., and some adults) have made smart things, such as robots that work together to sense intruders. "I think we'll begin to see more communities of toys that talk to each other," says Mitch Resnick, who worked on Mindstorms at the Massachusetts Institute of Technology. Just what Mom and Dad need.

Technology's potential to revolutionize the way children play has plenty of people excited, but it also has them dreading the way that technology might be used. "Prepare yourself for 80 million gimmicky, dreary toys equipped with every bell and whistle," warns Microsoft's Strommen. Others are worried that manufacturers will assign a gender to every smart toy they touch, relegating our kids to pink and blue stereotypes far into the next millennium. Another concern is price. Smart toys vary wildly, from $25 electronic sports games to $200 computerized Legos. As the price rises, the toy's depth and functionality increase -- a factor that could mean a smart-play gap between kids who can afford these toys and those who can't.

Whatever the toymakers do, they'll have to please another fun-starved customer, the grownup. About half of those playing with Mindstorms today are adults. "Of course I still play," says Furby's dad Hampton. "Designing these things is all fun and games, you know." And a pretty spectacular business.