The MetaWeblog API is a programming interface that allows external programs to get and set the text and attributes of weblog posts. This, along with the Blogger API, enables you to use a desktop or mobile client to manage your entries. As I'm running my own CMS I thought it about time to add a XML RPC service to it which actually turned out to be easier that I thought. I'm able to create and amend entries using the customer headers I need as well as Markdown formatting for content. The most "compatible" client I've tried is MarsEdit as Ecto (for which I have a license) seems to have issues with the CR/LF of the entries (I keep getting lines ending in #13). Obviously something I still need to work on there.
My ultimate goal is to be able to post using the Wordpress iPhone application but it seems to be quite picky in what services the XML RPC endpoint supports. Looking at the source code for BlogDataManager.m checkXML_RPC_URL_IsRunningSupportedVersionOfWordPress: I can see that if requires the following methods:
A call to "system.listMethods" needs to return those, all of which I should be able to hack in there in some form or another. Windows Live Writer on the other hand seems to be behaving a bit strange and won't even return a list of previous posts, something that all other clients have no issue with.