People who lived in the 60s were not all drug-using, free-love hippies. People in the 50s didn't ALL love Leave it to Beaver, and people in the 20s were not ALL Charleston-dancing flappers hanging out in speakeasies. Yet those are the images we have of those generations.

It's the perception that the history writers have of a generation that becomes the generation-specific brand. Facebook and Apple are two of the biggest brands. But some other, stereotypical brands may include Vans, skateboard companies, Red Bull, Abercrombie & Fitch, and YouTube. It just depends on what the media is reporting. And if the media is reporting that Gen Y is a bunch of iPod-listening, Red Bull-drinking, Abercrombie & Fitch-wearing young people, that's the image we're going to have in 30 years, regardless of what the students believe today. (Because it's the same thing the other generations believed about themselves then too.)

As many have pointed out here, it takes time to consecrate an icon. That fact alone means most icons will span one or more generations.

If someone thinks something is a generationally-specific icon, I'd bet it was more like a fad, trend or meme.

If I say “golf,” you think of Tiger Woods.
If I say “MP3 player,” you think of Apple's iPods.
If I say “search engine,” you think of Google.

These are all iconic brands. Are they specific to a generation? No, probably not. Google, iPods and Tiger Woods are icons of our time, regardless of whether you are age 10, 30, 50 or 70. Icons are limited to specific,historical time periods, but they will almost always span multiple generations.

As many have pointed out here, it takes time to consecrate an icon. That fact alone means most icons will span one or more generations.

If someone thinks something is a generationally-specific icon, I'd bet it was more like a fad, trend or meme.