This is a worthwhile topic for discussion because it's so hard today to even talk about the prevalence of marketing without sounding like a bitter Adbusters reader and feeling like a prick for bringing it up. Marketing is that ubiquitous and pointing out that we're all so used to it that we should hardly consider our own minds our own, is certain to elicit glares in polite company.
I was born in 1983 which means that even a child like me who was raised without television or video games has been a target of commercial marketing for his entire life. People my age were never little people -- we started out as "kids," which means we had our own taste and style and parents just didn't get it. Then, instead of being young adults, we were "teens;" which gave us new buying power and more money to spend. Somewhere in between we've all been "punk," "prep," "skater," etc. Corporate images that comfort with the illusion of identity. And now every facet of our lives seems to be open to manipulation.
Without exaggeration, it really does scare me to consider where advertising will go next.