According to Wikipedia, kaizen is defined like so:
Japanese for “improvement” or “change for the best”, refers to philosophy or practices that focus upon continuous improvement of processes in manufacturing, engineering, business management or any process.
Generally speaking, this is used to talk about the continuous improvement of a product. It’s also a core idea of lean manufacturing that has also been adapted into lean software development.
Anyway, the idea isn’t anything new and I honestly think now, more than ever, more people are familiar with the idea (even if it isn’t practiced) than ever before especially because some applications use the word in the release notes for their application.

Paper By FiftyThree mentions it with nearly every release.
As far as building products is concerned, this is something that I think many designers and developers want to do (if they aren’t already doing it, of course), but it are sometimes hindered by the nature of their environment.
By that, I mean that can we do continuous improvement – that is, can we practice kaizen – on projects that aren’t deployed on any type of particular schedule?