What does this signify?
P.S. No googling!

Answer: As correctly answered by karthik (and partially by anon), this is the evolution of the skype brand.
They chose to do away with the Akbar script(taken from the Simpsons) and the speechbubbles, and changed the tagline from "The whole world can talk for free" to "Take a Deep Breath", as a sign of greater things to come.