Andy Abramson tells us Why Google Doesn’t Need Skype. Good analysis. It boils down to capability and reach. They have the smarts to do it themselves, and they have the marketing reach to make it quickly successful. No need to spend $3 billion on Skype.
He also suggests that Google buy RIM before Microsoft does. I don’t think there’s any risk of the latter. Microsoft is committed to beating RIM in the market.