Is Media Concentration an Issue?

More on the notion that, for innovation and free society to flourish, the layers of any communication medium must operate independently. Many people believe that our current media landscape, dominated by a few vertically integrated mega-conglomerates, while threatened by the web, is just too concentrated.   I found this site that describes the Big Ten media conglomerates interesting.   While it's an update to this 1997 analysis it too is actually a couple of years out of date now. Since then BMG and Sony merged and GE  bought Vivendi.

What's the situation in Canada?  This is one perspective.  Does media concentration concern you?