Previously, a company could own tv stations that covered no more than 35% of the total viewership in the US. It's now been raised to 45%. Before, if you controlled a lot of the airwaves in, say, the New York area, you probably wouldn't be able to move into LA as well. You could heavily influence what a particular region sees on tv, but at least not the whole country. And the regional influence was tempered by the fact that you couldn't control both tv and print media in one place...but no longer.
Plus, consolidation of television, which is already pretty bad, is only going to get worse. Currently, most television is produced by "The Big 5", AOL-Time Warner (owners of the WB, and a lot of the major cable networks like CNN, TNT, TBS, and others. They also produce of a lot of the shows for the major networks), Disney (owners of ABC), Viacom (owners of CBS and UPN), General Electric (owners of NBC), and News Corp (owners of Fox). This means that even if you are an independent tv station, you still have to get your content from these 5 companies. There really isn't anyone else making TV shows anymore. I can't remember the exact numbers, or where I saw them, so take this with a grain of salt, but in 1990 or so, there were about 30 new shows on TV, and I think 17 were developed independently and sold to the networks. In 2000 there were again around 30 new shows, and I think it was 2 of them that were not developed by the networks themselves.
With the new 45% rule, there will be several tv stations in every major market owned by The Big 5. This means that independent stations are going to be competing directly with the same companies that supply them. That's a recipe for failure any way you look at it. It won't be long before virtually every media outlet in every major market is owned by one of the Big 5. I'm sure there will be some holdouts, but not many. This cartoon is a pretty good rundown of what this might look like :)
On a related note, I've just gained quite a bit of respect for Ted Turner. Check out this Op-Ed he wrote in the Post. This is a guy who has a *major* stake in AOL-Time Warner. He stands to make a lot of money from this decision, and yet he opposes it because he recognizes that as things now stand, there's absolutely no way someone could break into the tv business like he did. Now, granted, he's already filthy rich, he can afford to take a moral stance against something that will make him money. However, there are plenty of other people who can afford to take the high road and still choose not to. (I must note however, that while said person has been ruthless in the acquisition of his wealth, he has been very generous with that wealth once he has it.)