According to this new entry to the devturk blog, the stable (1.0) version of the Easyrest framework has been released.
Easyrest is a REST framework that contains client and server implementations.It has a easy structural data transfer unlike XML-RPC.Easyrest use a lot of pear packages and it has got custom apikey functionality.I think using the pear libraries is not a disadvantage because of you don't have to install required pear libraries, easyrest can work from its own custom pear directory without any pear installation.
The framework has got a custom API key functionality.User can assign client ids and API keys. It send raw data for HTTP Requests so it makes request very fast. The post includes plenty of examples for use on both the client and server side (including output).