The vague concept has been around, like in the sneaker and the Velcro story, but it took someone to get the two together together. But it's still not widely used. That's the beginning of contextual commerce. It's sill too banner related. They've lost me as a customer, which means they've lost the chance to build a customer for life with the current banner situation because the customers leave their site.
Contextual commerce takes it to the next logical step.
It's a progression. The Web is nothing but a progression of advertising techniques until we get it right. And that model worked for awhile. So contextual commerce, or getting users who are already, in effect, pre-sold for an item, is the next logical step. This isn't rocket science.