We've indeed given our RPC interface a massive overhaul, however the parts which have seen significant changes are internal ones. The actual JSON-RPC specification itself has not changed at all (i.e. web3's interface). We (go-ethereum) do not alone drive the specification for web3 and we require consensus between implementations (e.g. C++, Python, Java, Rust).

However our own RPC interface, which isn't included in web3, did change. We've removed and added functionality and cleaned up the mess that was included in some of the namespaces. At the moment geth supports the following transport layers:

HTTP

IPC (unix domain socket, Win named pipe)

IPC (in memory)

WS