Sparrow isn't the only big Mac developer that's switched to a high profile project today. Mac and iOS shop Acrylic has been called away from its own projects, including the apps Pulp and Wallet, by Facebook. The company doesn't say exactly what they'll be working on, but presumably it'll be the Mac and iOS interfaces for the popular social network (which, let's be honest, can use all the help they can get). Acrylic's Dustin MacDonald says the matchup "was a natural fit."
Facebook hasn't acquired any of Acrylic's projects, and those will remain available for download. Acrylic says it will post news of any updates or other work on its official blog, but helping design Facebook is probably a full-time job. Just like Sparrow, we're sorry to see a really great Mac/iOS developer move on from the projects we know and love, but we're also excited to see what work they can do on a bigger stage.