In my MonoTouch (iPhone) and Mono for Android code samples, I have a series of examples where I connect up to WCF/SOAP and REST web services. Its actually kinda painful to get the WCF settings right because the danged thing is so configurable. Getting everything configured right can take some time. Once you get all that done, the connection from iPhone and Android to those services is just like talking to any other WCF/SOAP or REST web service. Assuming that you are using Basic Auth, it just seems to work from that point. Given the general complexities of getting communications to work, this seems to be good enough for me.

BTW, did I mention that all of my services are exposed from Windows Azure? "To the Cloud"...................."Yayyyyyy Cloud."

PS.  I am hoping that Monotouch and Mono for Android give way to xTouch and xDroid soon.