What is old is new again
I'm looking at my three-year-old Nokia N9, running MeeGo, and I've always had Skype as a first-class citizen for phonecalls (a Skype phonecall can be placed through the "telephone app", just by pointing at a contact that has a Skype account) and messages (regular "Messages" app could send Skype, Google Talk, and even Facebook messages, before Facebook broke the API to segregate the messaging to the Messenger app). GoogleTalk videocalls, back when Google supported them, also worked the same way. Not having to use an app to make a call! Isn't that astonishing?
However, since I don't use Skype that often I can't be sure if all the message streams for a contact were fused, or if I have a stream for each kind of contact. I think they were fused but you could filter by network.
And I think Nokia Symbians (at least the N8/E7) could do the same. So good going, Nokia-now-Microsoft. It only took three (no, four) years to get back to where you were before committing seppuku. Congratulations.