Google released an FAQ detailing Protocol Buffers, along with source code for the Java, Python, and C++ protocol buffer compilers.

Sure, Java is still “write once, run everywhere”. Portability is still a central priority. But, now with Java 7 and Sockets Direct Protocol a whole lot more can be done with the Java VM.

Why did Google decide to go Open Source? "We have many other projects we would like to release as [O]pen [S]ource that use protocol buffers, so to do this, we needed to release protocol buffers first.