Makes sense, given that the ad-supported model the paper has been depending on isn’t working. Figuring out a paid model that will work will be challenging, but it’s certainly worth experimenting with. For more details, see PaidContent’s useful summary.

One other related point: Keller reiterates that the Times has a small but extant business on its hands via Amazon’s (AMZN) Kindle: For $14 a month, e-book readers can get a digital version of the paper delivered daily to their device.

I played with the Kindle for some time last fall and while I appreciate a lot about it, I can’t see why you’d pay $168 a year to read the Times on it: For one thing, the version that Kindle owners see is facsimile of the daily paper, which means it’s not updated with breaking news, even though the device has a wireless connection. Another negative–you can get the “live,” updated version of the online paper for free via the Kindle’s (admittedly crude) Web browser.

But people do like it, Keller says. How many? He won’t say, just that the business is “modest” (this also applies to the paper’s very, very niche Times Reader product). One hint: It’s generating much less than $10 million a year, which Keller describes wistfully as “real money” that the paper’s previous attempt at a subscription service generated.

Maybe those numbers get more significant as the Kindle becomes more popular: Citigroup (C) predicts the device will be a $1.2 billion business by next year alone. But I think the paper is going to have to find something more compelling to offer than a digitized version of last night’s news if it wants to charge a premium. I’m just not sure that offer should be.

Meanwhile Keller himself has a good perspective on it: “So some people are paying for The Times online. Just not enough of them. So far.”