Comcast has launched Skype on Xfinity networks in the Boston and Seattle areas today, with plans to roll out the service to a total of 10 markets by the end of the week. Comcast says the Skype application will allow “HD picture quality” video calling on big screen HDTVs. Customers will need Xfinity Internet service, an HDMI-capable Comcast cable set-top box and a Skype account to use the service. Additional markets to roll out Skype this week include Atlanta, Augusta, Ga., Chicago, Detroit, Harrisburg, Pa., Indianapolis, Miami and Pittsburgh.