Google Protocol Buffers

Google squirt a lot of data internally between a lot of different services written in different languages. The data format between these services has been tricky to manage. The default response is "use XML" but XML makes the data bigger and more costly to parse. Google's solution is Google Protocol Buffers. Create a .proto file to describe the data contained by a message you want to pass. Run a compiler and you get the Java, Python or C++ code you need to read and write messages with that protocol. Now go wire up your services. All under an Apache 2.0 License. Worth checking out; and it'll be interesting to see how long before that range of languages supported expands.