I'm Chris Hardy, a program manager at Microsoft working on the Xamarin Live Players. Yup, you will still need a Mac, to deploy to the app store, to work against different APIs that require special provisioning (such as Push Notifications, etc.), sign and provision applications to share via TestFlight. The goal for Xamarin Live Player is to provide an easier and faster way to work and iterate on applications with C# and Xamarin without the need to commit to downloading and provisioning different devices to get up and running.