Over half a million viewers have left NBC Nightly News
All this talk about how Katie Couric is single-handedly destroying network news (supposedly) overlooks one fact: she's actually losing less viewers than Brian Williams over on NBC.
Couric lost 287,000 viewers over the first 39 weeks of her show compared to what the show did last year, and during that same time, Williams lost 533,000. He's now in second place behind ABC and Charles Gibson.
Of course, it doesn't mean that everyone who is leaving NBC or CBS is going over to ABC and Gibson. I think it's an indication of what's going on with network news in general (and NBC in particular).