Actually, the mainstream media DOES know about Linux...they just choose to cherry-pick exactly when and where they'll mention it. CNN Headline News actually had a live interview with Michael Robertson of Lindows (now Linspire). I think the only reason they decided to interview Robertson was because of Microsoft suing Lindows over the Lindows name. Plus, msnbc.com reviewed Linspire Five-0 on their site last year (gave it a positive review). Now if they could have been considered mainstream media, TechTV frequently talked about Linux. Marcel Gagne actually appeared on an edition of "Call For Help" last year on G4. But lately G4 has been moving away from games and computers in an attempt to be a Spike TV rip-off.
I'm gonna attempt to do in-depth research on the mainstream media's coverage of Linux. I'm gonna research on CNN, Fox News, MSNBC, and so on. What I find, I will post here.