Google is suing Skyline Software Systems over patents purchased in Google's recent acquisition of Keyhole. I wonder if they'll be going after NASA next. NASA's WorldWind is a free, open source C# application that does something similar to Skyline's software and Keyhole.
[UPDATE: The article linked to above has changed since I originally posted this. It now says (as Chris Dibona states in my comments) that Google's filing is a response to a lawsuit filed by Skyline.]