Some screens of the update in place:
A succession of intro screens show off the concept, with messages in blue coming in via Skype and those in dak grey via SMS. It's very analagous to Apple's iMessage in concept, though here tied principally to your Microsoft account.
There's an optional tie in via your phone number too, to help link up new Skype contacts; (right) interestingly, this does nothing to disturb the old/existing Skype client. In theory this is redundant (though it still works) - I'm guessing that this will simply not be available anymore for new installs once Windows 10 Mobile is finished.
Go check it out, and comments welcome. Does this simplify things for you or complicate them?(!) And how well did it do picking up your existing Skype contacts? I'm going to be monitoring this over the next days and weeks....