1. Skype is central to the online experience. It is one of those companies who's name has become a verb due to the high uptake of their technology
2. Skype's business strategy is to offer free PC to PC calls, and charge for calls from PC to other devices, and enterprise usage. The free, ad-supported PC to PC calls have served Skype well, but they have been weak on the premium side. Microsoft will help maximise the premium side by mixing Skype into all of their hardware products(Windows Phone, Xbox etc) and ALL their enterprise products(MS Office, Outlook etc)