Over the years Google has been slowly making it easier for people around the globe to have the ability to buy apps, games and other content in the Play Store. In the early days you could only do that with a credit card that was attached to your account. Not everyone had a Credit Card/Debit Card. As the years went on Google allowed carrier billing with a number of service providers, introduced Google Play Gift cards and more recently, added PayPal. When the option to pay with PayPal was added it was available in 12 countries, including the US.
Today, Google quietly slipped Australia, New Zealand, Greece, Portugal, Singapore and Sweden into the mix on their Google Play payment support page. THat brings the list up to 18 locales where you can use PayPal to buy devices, accessories, apps, games and other items outside the Play Store with Google Wallet.
Source: Google Play Via AndroidPolice