As previously rumored and now confirmed, if you have the Xbox Game Pass Ultimate, which includes Xbox Live Gold and Xbox Game Pass, then you also have Xbox Game Pass PC Games. Otherwise, the subscription looks to cost $4.99 per month and will require Xbox Live Gold.
I have been part of Xbox Game Pass Ultimate for a couple of months now in pre-release testing and it is by far the best deal now that we know the PC games are part of that subscription along with the console games that are available. Both the console and computer based subscriptions have over 100 games in each library so you can not beat the price of $15 per month for a game library of that size plus Xbox Live Gold.
Access to the Xbox Game Pass PC Games is through the new Xbox App which is in beta and available today. That app not only lets you browse the Xbox Game Pass PC Games library but it also gives you access to social activities on Xbox such as chats and your friends list.
In addition, there is a store that gives you the ability to purchase games that are available on the Xbox Game Pass PC Games if you want to permanently own them. It looks like they will be available with the expected 20% discount but many are discounted even further due to Xbox E3.
Below you will find a gallery of screenshots of the new app to help you become familiar with the layout.
Xbox App (Beta) and Xbox Game Pass PC Games Screenshot Gallery