Many divide baby-boomers between "early" (the ones who get all the glory) and "late" (in fact, the largest population born in the US until the 1990's). I was a late baby-boomer, who grew up as technology was being developed. As technology is always changing, the question is (as you so aptly put it) when would there be a generation of "natives"? While the technology might be different, those of us in the late boomers grew up in the age of computation (electronic calculators, mainframe computers, the logic of electronic computation, flow charts). As we have grown, so has the digital landscape. But is there a parallel time line for those that were not part of the electronic age (i.e. the loss of technology which forces people to move to other tools, such as the end the lazer disc, the floppy disc, the manual type writer, the console, the mainframe computer)? This would allow you to see the gap between digital natives and digital immigrants (i.e. the waves of immigration).
I'm with Karyn Romeis about using the imagery of digital natives or immigrants: I'm on the fence with it. That said, I wonder if, like waves of immigration to the US and Britain, if there have been waves of immigration to the digital environment that then impacts technology and programs.
The first wave might be at the advent of the PC and Mac in which the computer was now in the home, which led to word processing and financial software. The next wave was the development of the internet which led to such programs as email ( remember when it was all done in code) and the world wide web. As more people bought PC's and Mac's to access information through the web, more web based programs were developed, leading to another wave of immigration to access information, communicate, and conduct commerce on the web. High speed web integrated with phone and tv service meant that another wave of immigrants entered the digital landscape to access entertainment, videos, tv, music (ipods, mpg players).