Google just changed the name of the Android Market. From now, Android Market will be called as the Google Play. It is a step to give the branding of the Google to the Android app store.
An update will be available for the Android Market soon which will convert the Android Market into Google Play. But the changes will not be same for all over the world. As stated,
In the U.S., music, movies, books and Android apps are available in Google Play. In Canada and the U.K., we’ll offer movies, books and Android apps; in Australia, books and apps; and in Japan, movies and apps. Everywhere else, Google Play will be the new home for Android apps. Our long-term goal is to roll out as many different types of content as possible to people around the world, and we’ll keep adding new content to keep it fresh.
Hope that it will not create confusion among Android users and they will keep enjoying their phones with lots of useful apps and games like earlier.