Skitch, a popular Mac desktop app for quickly snapping, marking up and sharing screenshots, has been acquired by ambitious archiving service Evernote, the companies announced today. Also announced: Skitch for Android, iPhone and iPad. The Android version is available today but, unfortunately, appears to focus on annotation of photographs instead of helping capture the elusive Android screenshot. Skitch for iOS is "coming soon."

What does it mean that Skitch is now part of Evernote? It means that the international team behind one of the most-loved little pieces of Mac software, which makes it so easy to capture content and throw it up on the web, has now found a home in a well-funded startup with very long-term archival aims. It's a good sign for Evernote's design and user experience, too.

Evernote says that Skitch's most advanced features, which today sell for $20, will now be free forever. We interviewed Evernote CEO Phil Libin last November and found out that the company works under a nearly 20 year plan and believes that in that timeframe, people will have brain implants that let us invoke the Internet with our thoughts. Evernote will be there to capture those assets, too. At least now we know that will be done with an attractive, Skitch-like interface.

Alternatives include Aviary, Little Snapper and many others. See also Springpad.