@coderus: what does one need to make such client work?
QtContacts? QtMultimedia? what else?

I could consider working on something like this. Actually what i'd like to do is a barebone qt application for mobile instant messaging.
I see you guys all follow the interface of wazapp, which is cool.
Sadly is also closed source, so it would be cool to have the app without the whatsapp inside, GPL hopefully, so that people can customize it and support the various protocols (which in the end i hope to be one and open).