Who says they need to?
Google Secure Access will work equally well from the desktop (and it's working right now from London actually - and over WiFi from Swisscom AP's in London, so this whole San Francisco thing is a red herring).
What it does is create a new VPN sub-net running on the internet backbone from which only Google can mine data and information.
Now how powerful is that for an advertising company? Dark fibre anyone?
And re: Skype - as a leading industry blogger put it this afternoon : "why buy a company when you can swallow it?".