using instant messaging api for client server communication

I was thinking of using some sort of existing instant messaging api to implement client/server communication for sending commands and receiving data (controlling a server side process with a smartphone and receiving data encoded in something like XML to reflect status)

Are there any problems with this idea other than latency? Is there a generic "IM" api available (something like Trillian, where the user could specify any IM service) or even a chat client that has an api for android and Windows that would be good for this?

Facebook and Google chat clients seem to have a comprehensive api, but I think I'm understanding that they will use integrated authentication, and thus the data and commands will be visible if the user uses those services and opens the "real" apps - unless I'm misinterpreting it or I'm not seeing how to specify sending and receiving messages as a different user while allowing other clients to remain logged in as their "real" account.

Is there a chat service that has an api without integrated authentication? Am I barking up the wrong tree?

EDIT, based on comments:

What technology or framework/api is best suited for this type of communication (platform neutral, server-client communication, for issuing commands and receiving status in more-or-less real time)?