Bank-industry analyst Meredith Whitney, one of FORTUNE’s Most Powerful Women and the subject of our cover story last summer, is all over the place this week. An op-ed, “Credit Cards are the Next Credit Crunch,” in today’s Wall Street Journal presents a dreadful outlook for consumer spending. She says that she’s upped her estimate for how much banks will yank credit lines to consumers–by $2 trillion this year and a total of $2.7 trillion by the end of 2010.

Lenders have to retrench, having extended credit way too freely for the past 15 years. But what’s really scary about such a dramatic pullback, Whitney says, is that lenders will be taking credit away from people who are able to pay their bills. And given that two-thirds of the U.S. economy depends on consumer spending, this will seriously retard any recovery.

Whitney doesn’t name lenders in her WSJ piece, but in a report that she sent to clients today, she lists the five companies that control two-thirds of the market: J.P. Morgan Chase , Bank of America , Citigroup , Capital One and American Express . While customers have a mortgage loan from just one company–a “monogamous relationship,” she notes–the typical credit-card customer borrows from more than one of these lenders. So, she suggests: “These lenders need to work together…by setting consortium guidelines on credit. We, as Americans, are all in the same soup here, and desperate times are requiring of radical and cooperative measures.”

Meanwhile, there’s a very good Q&A, titled “The Straight Shooter,” with Whitney in a magazine called
, just out. In the interview, she talks about chatting up Warren Buffett at Fortune‘s Most Powerful Women Summit last October. The topic: paper routes. Here’s an excerpt:

“When I was about eight or nine, I told my mother that I had to have my own money. And that led to the newspaper route. It was just run-around money. In fact, the first real thing I bought was a watch for my mom, which she still has. I was very good at delivering papers and was able to buy up other paper routes. At the FORTUNE women’s summit in October, I didn’t want to bug Warren Buffett, who was there. But I needed to talk to Carol Loomis [FORTUNE senior editor-at-large], who was with him. I couldn’t help myself and said to him, “Thank you for providing such comfort at a time when most Americans are scared to death.” And he said, “Tell me about your paper route.”

If you had a real paper route, not just a casual hobby, you will talk about it all day long. And I said, “Well, I’ll tell you about my paper route, but I need to know a few things. Was yours a bike route or on foot?” And he said, “Bike.” And I said, “That is such a different experience because my paper route was on foot, so I don’t know if we can compare ourselves.” I would go up to the front door, put the paper behind the screen door and get better tips. And so I asked Warren Buffett, “What was your best tip?’ And he said, “$1.” I asked him what that would be adjusted for inflation. And he said, “$10.” I got $20.”

As you may know, Whitney last month quit Oppenheimer & Co. to set up her own shop, Meredith Whitney Advisory Group. If she carries her paper-route business sense into adulthood, I think she’ll make a go of the new venture.