It took 18 days for Egyptian protesters to topple Hosni Mubarak’s 30-year regime; it took about 10 days for the editors at Foreign Policy to publish a 70,000-word ebook about the revolution.

“Revolution in the Arab World” is FP’s second attempt at a new publishing model — call it the medium form — to quickly repackage its own reporting and charge for it (in this case, $4.99). The stories inside are already on the web, free, but the magazine hopes readers are willing to pay for the context of a compilation and the convenience of a single download.

It’s about “putting this smart journalism in front of people outside the very, very fast web cycle — but while it still matters to readers,” said Susan Glasser, Foreign Policy’s editor in chief. The medium form, more comprehensive than a story but less so than a traditional book, is a fast and inexpensive way to satiate readers who demand information right now.

One thousand copies of “Revolution” sold in the first 10 days, Glasser said.

Foreign Policy is one of a number of news organizations experimenting with journalism-as-ebook. The New York Times recently published an ebook of reporting on the WikiLeaks story for $5.99, and we’ve written about ProPublica publishing Sebastian Rotella’s 13,000-word piece on the Mumbai terror attacks as a 99-cent Kindle Single, Amazon’s new format for inexpensive, 30- to 90-page stories. That ebook sold 3,500 copies in about a month.

For “Revolution,” the FP editors reviewed a year of their own reporting and selected about four dozen stories they deemed to have lasting insight and value. They decided on a structure of six chapters, opening with a January 2010 piece from Issandr El Amrani that presciently describes Egypt as a “ticking time bomb.” The pieces were updated, lightly edited for clarity and dressed up with introductions from the editors.

Glasser views this midform journalism as a low-impact experiment; the pricing was chosen because Glasser said, as an iPad owner, it just felt right. “Listen, we’re testing it out. We don’t know. We’re a small organization trying to figure out the business,” she said. Foreign Policy employs 30 people.

The magazine’s first ebook — a series of dispatches from Anna Badkhen in northern Afghanistan — has sold 5,000 copies, at $2.99 each, since September. That title is available exclusively for the Kindle in an arrangement with Amazon, which published and marketed the book in exchange for a much higher cut than the 30 percent the company normally takes. The process took “months of back and forth,” Glasser said, and felt very much like onerous, old-school publishing.

For the second book, Glasser opted to self-publish. “We decided the tools have become even easier and there’s more possibility for us to do it directly and quickly ourselves,” she said. “Revolution” is available in three formats — Kindle, PDF and, soon, iBooks — but the magazine is pushing the PDF version on its website to rake in more proceeds.

The trusty PDF has its own drawbacks. There is currently no way to prevent readers from “sharing” the file to avoid paying. And while it’s easy enough to buy the PDF through PayPal and transfer the file to an e-reader, nothing beats the seamless, impulsive experience of one-click purchasing and downloading that Amazon’s and Apple’s platforms provide.

The market for repurposed journalism is still evolving. Consider how much changed for ProPublica in the two weeks between its first and second Kindle Single. After selling thousands of copies of the Mumbai piece, a deeply reported piece on oil drilling hit the Kindle Store at a price of $0. Amazon had a change of heart, reasoning the material should be free in the Kindle Store if it’s free on the web.

But even with their fickle rules and hefty cuts, vast marketplaces like Amazon’s are too big to ignore. Glasser said her piece of the pie is search — reaching readers who take interest in the subject but would never visit her website. Before publishing “Revolution,” Glasser ran a quick search in the Kindle store. “I realized there was nothing about Egypt except a bunch of tourism guides…and a bunch of old mummies-and-pharaoh kind of books,” she said. (Search for “egypt revolution” on Amazon.com today; Glasser’s ebook is No. 1 in the Kindle Store and No. 2 sitewide, behind a 2008 book.)

I asked Glasser what would qualify as a wild success: reaching No. 1 in Amazon? Two thousand copies? Ten thousand? She laughed — she doesn’t know. If nothing else, she said, the ebook is a really satisfying way to give good journalism a longer tail. “We’re publishing so much stuff on our website, and the news cycle is so quick. Some of it is wonderful magazine-quality thinking and reading, in real time,” she said. “It goes so quickly.”

Glasser expects Foreign Policy will publish more ebooks this year, but she doesn’t know yet what they might cover. That’s kind of the point of this new model — we can’t predict the next Wikileaks or Libya, but the medium-form ebook is a way for newsrooms to react swiftly and nimbly — and maybe even make a few bucks.