Can someone explain why Protocol Buffers (http://code.google.com/apis/protocolbuffers/) is not being used more widely?? It it 'cause of the limited language support (Java/C++/Python only) or some other reason??
Google also kept the RPC side of Protocol Buffers, which is called Stubby, as an internal project.
Protocol Buffers has limited language support, the implementation in one popular language (Python) blows goats, and even though it predates Thrift it was not released until after Thrift arrived so its community is smaller. The number of people who need this sort of product is relatively limited, so the early traction that Thrift has gained will take a bit of time or some compelling reasons to overcome.
Myself, I've stopped using protobuf because it's super slow in Python.