Twenty years ago, only big companies and TV stars worried about media channels.
Oprah was on TV, then she added radio. Two channels. Then a magazine.
Pepsi set out to dominate TV with their message, and billboards and vending machines. Newspapers, not so much. The media you chose to spread your message mattered. In fact, it could change what you made and how you made it. [Stop for a second and consider that... the media channel often drove the product and pricing and distribution].
Today, of course, everyone has access to a media channel. You can create a series of YouTube videos, or have a blog. You can be a big-time tweeter, or lead a significant tribe on Facebook.
Harder to grapple with is the idea that the media channel you choose changes who you are and what you do. Tom Peters gives a hundred or more speeches a year, around the world, for good money (and well earned). But this channel, this place where he can spread his message, determines what he does all day, impacts the pace of the work he does, informs all of his decisions.
Oprah lives a life that revolves around a daily TV show. Of course it would be difficult for her to write a book... that's a life dictated by a different channel. And she's a lapsed twitter user because it demands a different staffing and mindset than she has now.
This applies to non-celebs, to people with jobs, to entrepreneurs, to job seekers. We all spread our ideas, at least a little, and the medium you choose will change your ideas. If you only pay attention to the world when you need a new job (your channel is stamps and your message is your resume) you'll spend your day differently than if you are leading a tribe, participating in organizations or giving local speeches all the time.
We've come a long way from a worker having just two channels (a resume and a few references) to having the choice of a dozen or more significant ways to spread her ideas. Choose or lose.