Google rolled out carrier billing for Android apps in the Android Market some time ago, working with a number of networks around the world to make it available to subscribers. It's convenient since it rolls charges right into your monthly phone bill — so convenient, in fact, that the company has expanded it this week to all types of Google Play content: apps, music, movies, and books. Unfortunately, the expansion once again requires that Google work with each carrier individually, so it's not immediately available on all carriers where app billing was already available — initially, T-Mobile in the US along with NTT Docomo, KDDI, and Softbank in Japan are rolling it out. Sprint will be following "soon."