The latest preview release of the Configuration Manager 2012 SDK has been posted to TechNet. Link: http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=29559
One of the exiting new features in this SDK is the Client Messaging SDK. This SDK is meant to replace the old MP API. It not only provides means for sending messages to a management point (just like the old MP API), it also provides you a full object model encapsulating a large majority of the messages to a management point. This removes all of the previous headaches around having craft your own request messages and response parsers. You can literally use 5 lines ot code to register a client. More will be posted here soon with samples and other great ways to use this SDK to implement your own custom client on Configuration Manager.