This article from Adbusters discusses an ongoing case in Canada that they're brought against the Canadian government and some of the largest corporations that control Canada's media. Although this is Canada, we face the exact same problem here in the States, and it's doubtlessly all over the world. Although the Internet and all the doors that it's opened in terms of democracy and speech has been tremendous, television is still the largest medium in terms of media and information. Since the airwaves belong to us, ensuring that we control them and that our voices are heard, rather than having corporations tell us what they think we should hear, is of utmost importance.
Personally, I don't think our corporate media in the States deliberately suppresses information so much as they indulge the collective idiocy of the American people. I'm not saying that most Americans are idiots; but just in terms of news and information. I see it all the time, you'll lead more people to your newscast by talking about Britney Spears, the Petersons (be it Mark and Laci, or now it's Tracy), or the pregnant Marine who was found buried in a backyard. But let's take issues (rather than people), like Iraq, global warming, the economy, etc. Yeah, these get covered too, but at a much lesser rate. And when they are covered, it's often in a blurb, or a brief segment. You don't have hours devoted to global warming or the recession like you do with Britney Spears. Because people find issues boring. And we have a corporate media who, like all things corporate, wants to make money. So rather than act as a responsible medium and encourage people to smarten up, they decide to go for the easy advertising dollars by dumbing people down with these non-issue stories.