As Motoko Rich and I report in Wednesday’s New York Times, Amazon.com is finally opening up the Kindle to developers. This has the potential to turn a popular single-purpose device into a more interesting and versatile gadget, limited only by the imagination of third-party programmers — and by what they can do with its monochrome e-ink screen.

/Ben Margot/Associated Press

Amazon says it has already released the Kindle Development Kit to a select number of partners, including the video game giant Electronic Arts, and will make it more widely available when a limited beta period starts next month. It anticipates formally adding what it calls “active content” to the Kindle store sometime later this year.

Ian Freed, Amazon’s vice president for the Kindle, said there would be three different categories of active content: free applications, one-time paid applications, and applications that require a monthly subscription. Kindles that have already been sold will be able to run these programs once Amazon has remotely upgraded their software.

Developers will get to suggest their own prices for their programs, but they will have to shoulder the cost of wireless delivery at a rate of 15 cents a megabyte. After those costs are covered, developers keep 70 percent of the revenue from the sale of the app, while Amazon keeps 30 percent. (Remember that unlike smartphones, the Kindle does not require a monthly wireless fee.)

How actively will Amazon police what makes it into the Kindle store? “The guidelines are what you might expect,” said Drew Herdener, an Amazon spokesman. On the forbidden list: Internet voice-calling software, advertising, offensive materials, the collecting of customer information without consent, and the use of the Amazon and Kindle brands.

One company that’s had access to the Kindle development kit is Handmark, based in Kansas City, Mo., which brings Zagat restaurant guides to mobile devices.

Handmark is creating a version of the guides for the Kindle, said Paul Reddick, its chief executive. The book will, among other things, be searchable (type in “Italian restaurant,” “New York,” and kid-friendly,” and get the relevant restaurants), and will allow people to type in a ZIP code and find restaurants in their area.

Mr. Reddick said he did not think the drawbacks of e-ink – monochrome screens, minimal graphics support – would necessarily limit the variety of applications available for the Kindle: “If you are trying to play some twitch game it might be a limitation. But for Zagat, it’s a really good fit.”