At Google I/O last month, the company announced a slew of new API's. One of those was the new Awareness API, which allows developers to see what you are doing. This API gives them a general sense of what you're doing (i.e. browsing Facebook, searching Google, etc) and not the specifics. With the Awareness API, there are basically two ways that developers can monitor their users' status. This includes the use of the Snapshot API and the Fence API.
Now the Snapshot API here allows the app to easily request information regarding the user's current context. So the developer could have the app return the user's current location and current weather conditions. Which can be useful for a slew of different actions within an app. Meanwhile the Fence API allows your app to react to changes in user's context. As well as when it matches a specific set of conditions. It's pretty similar to the Geofencing API that's already available with Android.
Many users likely won't notice that an app that they use, uses these new API's. But they can come in handy. Imagine an app knowing that you are walking outside and have headphones plugged in or paired over Bluetooth. It could ask you if you want to start playing music, without you needing to even open the app. Additionally, if it has your current location and weather data, it could send you a quick notification saying it's about to rain, or a bad storm is on the way. Making things much easier for users. But then on the other hand, this API could become pretty annoying and will likely be abused by developers. Especially when it comes to ads. Luckily, most apps will allow you to turn these types of notifications off, if you wish.
According to Google, this new API is part of Google Play Services 9.2, which has already rolled out to everyone. This means that if you are using an app that uses these new Awareness API's, you should see these notifications coming in rather soon. It's pretty likely that most apps don't actually use the Awareness API, or the Snapshot API and Fence API, just yet.