Digg owner BetaWorks has acquired Instapaper, a highly acclaimed app that saves articles on the web for later reading. Instapaper founder Marco Arment announced the acquisition on his blog, saying he would remain an advisor indefinitely, but that Betaworks will take over Digg operations, expand its staff and develop it further, as competition in the reading space heats up.

Betaworks is a start-up studio and seed stage venture capital company based in New York City, which most notably took over the struggling Digg and turned it into the web product it is today. Arment didn't disclose for how much he sold Instapaper to Betaworks, but confirmed he sold a majority stake. 

Instapaper was launched in 2008, to let users clip web articles with a "Read Later" browser bookmarklet. Articles are then presented in a minimal, readable text layout for easy use. There's a web, iOS, Kindle and unofficial Android app available. Arment has shown his Android disgust from time-to-time. Coincidentally, the Instapaper app was highly regarded when the iPad launched in 2011. 

Arment didn't go into the details on why he sold Instapaper, except that he "had a lot of trouble keeping up with it". Betaworks has the resources to keep Instapaper chugging along. "I wouldn’t put Instapaper in just anyone’s hands, and I know that they’ll do right by it," wrote Arment.

Instapaper will remain available on all platforms. It will be interesting to see what direction Betaworks takes. Could it potentially be integrated into Betaworks' proposed Google Reader replacement?

As for Arment, we assume he'll stick with The Magazine, an iOS Newsstand publication that features many different writers in each issue.