Skype is now letting Windows 10 users send money over the service via PayPal, albeit with the feature only in testing at the moment. However, the capability should be coming to the release version of Skype soon enough.
Previously, this feature has been available to mobile users of Skype on Android and iOS, and as MS Power User spotted, it’s now live for Windows Insiders testing preview releases of Skype (you’ll need to grab version 14.32.42.0).