The de facto Queen of All Media has gone digital. Last week, Amazon’s Kindle e-reader got a powerful celebrity endorsement from Oprah Winfrey, who declared that the gadget is “absolutely [her] new favorite thing in the world.”

Oprah acknowledges the prohibitive price of the device (she was apparently given hers as a gift — Quillblog will refrain from comment…), but suggests that it will pay for itself in the long term:

Although the Amazon Kindle costs $359, Oprah looks at it as an environmentally friendly investment. “I know it’s expensive in these times, but it’s not frivolous because it will pay for itself,” she says. “The books are much cheaper, and you’re saving paper.” New York Times Bestsellers and New Releases are $9.99 or less, unless otherwise marked.

Meanwhile, The Bookseller wonders whether the Kindle will benefit from the same “Oprah effect” that individual books experience when the ubiquitous talk-show host bestows her blessing upon them by naming them to her book club.

Media commentator Greg Sandoval writes on CNET that it is “unclear […] how much impact her endorsement will have on the Kindle. The good news for Amazon is that Oprah’s adoption of the Kindle is a signal that the device is transitioning from early adopters to the mainstream. Amazon played up Oprah’s glowing testimonial by posting clips of her show on its front door.”

There are rumours of a new version of the Kindle due out next year; CNET’s Dan Farber asks whether Oprah’s endorsement will allow Kindle 2.0 to achieve “escape velocity.” Quillblog expects that with the U.S. economy tanking, consumers will be unwilling to lay out $359 to purchase a Kindle this Christmas (the device is still unavailable in Canada). There are some things that even Oprah can’t influence.