Some services included in the Google API suite include Ad Exchange, Blogger, Google Compute Engine, Drive, Google+, Tasks, Translator, YouTube, etc. This is an open source library that allows programmers to use .NET integrate Google services into Desktop and Windodws Phone applications. You can refer here for a complete list of services and download the API suite for .NET at NuGet.
Although until now, Google has not yet released any genuine applications for Windows Phone or Windows 8 except the Google Search search engine. However, with the provision of a new API library, we will have better alternative applications to exploit Google services from developers.