Betaworks acquires Marco Arment’s read-it-later platform Instapaper

New media incubator and venture firm Betaworks has acquired a majority stake in Marco Arment’s read-it-later platform Instapaper, the companies announced Thursday evening. Other Betaworks companies and projects include, Chartbeat and Done Not Done. The firm acquired Digg for a reported $500,000 last year.

Unlike Digg at the time it was acquired, however, Instapaper has a business model: It’s a paid product. The iPhone and iPad (s AAPL) apps are $3.99, and the Android (s GOOG) app is $2.99. Users can also install a bookmarklet to save articles.

On his blog, Arment wrote of the acquisition, “We’ve structured the deal with Instapaper’s health and longevity as the top priority, with incentives to keep it going well into the future. I will continue advising the project indefinitely, while Betaworks will take over its operations, expand its staff, and develop it further.” He said he has been looking for an opportunity to “try other apps and creative projects.”

Betaworks’ acquisition of Instapaper fits with the firm’s strategy of investing in both short and long-form content. Betaworks CEO John Borthwick said at the paidContent conference last week that companies shouldn’t favor one over the other: They need to invest in both. Digg is planning to launch a Google Reader replacement, and Instapaper’s technology could possibly be put to work on that project.

Here’s a video of Borthwick talking to Om Malik at paidContent Live: