Which version of the JSON-RPC protocol does Bitcoin use? I would like to get some clarification on which version  of the JSON-RPC protocol does Bitcoin use? 1.0 or 2.0?
A little of both:

//
// JSON-RPC protocol.  Bitcoin speaks version 1.0 for maximum compatibility,
// but uses JSON-RPC 1.1/2.0 standards for parts of the 1.0 standard that were
// unspecified (HTTP errors and contents of 'error').
//
// 1.0 spec: http://json-rpc.org/wiki/specification
// 1.2 spec: http://groups.google.com/group/json-rpc/web/json-rpc-over-http
// http://www.codeproject.com/KB/recipes/JSON_Spirit.aspx
//