That was also something I absolutely loved on N9 and N900. Now I have to do with Android-version of Skype, but as far as I know, many of those communication tools in N9 were built on top of one framework to integrate them to unified user experience. Sailfish already has XMPP, but does it have Harmattan-style framework in place already? If it does, it shouldn't be too difficult job to develop many of those tools from Harmattan-versions.