From Microsoft News | Microsoft Announces Skype For Outlook.com In Various Countries Including US:
I guess it shouldn't come as a surprise seeing as how Messenger was incorporated in Hotmail.
Microsoft today announced the availability of Skype for Outlook.com in several countries around the globe including the United Kingdom, Germany, Brazil, France, Canada, and the United States. Microsoft also said that for the those in the other countries, they are still working hard to ensure it is available worldwide in the near future.
I guess it shouldn't come as a surprise seeing as how Messenger was incorporated in Hotmail.