Yes, according to one study of American children. Excerpt:

Kyung Hee Kim at the College of William & Mary discovered this in May, after analyzing almost 300,000 Torrance scores of children and adults. Kim found creativity scores had been steadily rising, just like IQ scores, until 1990. Since then, creativity scores have consistently inched downward. “It’s very clear, and the decrease is very significant,” Kim says. It is the scores of younger children in America–from kindergarten through sixth grade–for whom the decline is “most serious.”

Why might this be? More from Newsweek:

It’s too early to determine conclusively why U.S. creativity scores are declining. One likely culprit is the number of hours kids now spend in front of the TV and playing videogames rather than engaging in creative activities. Another is the lack of creativity development in our schools. In effect, it’s left to the luck of the draw who becomes creative: there’s no concerted effort to nurture the creativity of all children.
Around the world, though, other countries are making creativity development a national priority. In 2008 British secondary-school curricula–from science to foreign language–was revamped to emphasize idea generation, and pilot programs have begun using Torrance’s test to assess their progress. The European Union designated 2009 as the European Year of Creativity and Innovation, holding conferences on the neuroscience of creativity, financing teacher training, and instituting problem-based learning programs–curricula driven by real-world inquiry–for both children and adults. In China there has been widespread education reform to extinguish the drill-and-kill teaching style. Instead, Chinese schools are also adopting a problem-based learning approach.

Good for the Chinese. Meanwhile, we soldier on with the egalitarian shackles of No Child Left Behind. When I first read this news, my thought was that NCLB has a lot to do with this, but I re-read that the decline started around 1990. That makes video games and computer obsession a prime culprit, it seems to me. Alan Jacobs speculates that the hyper-managerial style of parenting that has become common with the middle classes has a role. Along those lines, I have heard from veteran high school teacher friends that their brighter kids over the years have become so timid, for fear of getting the Wrong Answer, and Not Getting Into Harvard. Fear of failure and related status anxiety is a sure-fire way to kill creativity.
UPDATE: Steve Sailer’s thoughts here. I wanted to add something of my own, too. I was just thinking about my son Lucas, who is six now. His uncle, my wife’s brother, has a natural gift for music. He plays the piano beautifully by ear, and would cheese off his older sister (my wife) when they were kids by coming up to the keyboard, where she was practicing, and playing something lovely, though he didn’t read a word of music. Something genetic is plainly at work there. Well, Lucas resembles his uncle more than any of my other kids do. It wasn’t surprising to me when, a couple of years ago, we were visiting Julie’s brother and his wife in Austin, and Lucas scampered over to the piano and started banging. After a few minutes, I pointed out to Julie that there was reason in his plonking — that he wasn’t just pounding keys. We’ve observed that in him on subsequent occasions, and seen too that he has an unusually attuned sense of rhythm. So we bought him an electronic keyboard. He likes to fiddle with it, but he’d much rather play with Dad’s iPhone, or the Wii. I can tell already that if we’re going to get him to explore the innate creative gift for music he seems to have, that we’re going to have to strongly limit his access to passive electronics.
For that matter, if his father is ever going to write another book, he’s got to get off the damn Internet. But that’s another story. Or is it?