Does iPhone support XML-RPC, Is their any open source framework which I can use?
"Airsource Ltd" is really really incredibly wrong about that document. That document is specific to Mac OS X and NOT the iPhone. In fact (almost) all Apple iPhone documentation is hidden away behind a login page and a licence agreement. Most of the technologies that document refer to (e.g. AppleScript) do not even exist on the iPhone.
Amit, you'll have Zero luck if you follow Airsource's advice. You will however do ok if you do as "Lounges" says and go grab the wordpress source code. It looks like they rolled their own XMLRPC library for use on the iPhone.
As for SOAP - you're on your own. You might be able to find an opensource SOAP library built on top of libxml2 though. Good luck.