From c|net:
"By Stephen ShanklandCheck out the entire article on c|net.COLOGNE, Germany – Beefing up its telephoto lens line, Canon plans to revamp an aging 100-400mm zoom and bring a novel technology called diffractive optics to more models.
Lenses are key to camera company profits: the more lenses a photographer has, the harder it is to move to a rival's system of camera bodies and lenses. And unlike camera bodies, lenses don't go out of date so fast, which means they're more profitable to sell once investments in engineering and manufacturing are paid off.
The 100-400mm zoom is a good example. Canon introduced it in 1998 with its first-generation image stablization technology, which counteracts some camera shake, and still sells it for $1,700. But a new model is in the works, said Canon technical advisor Chuck Westfall in an interview here at the Photokina show Monday. "It's definitely on the boards for replacement," he said, though declining to say when.
In addition, Canon is working to spread a technology called diffractive optics, or DO, into more lenses, he added – maybe even cheaper lenses..."