Google has made it clear at Google I/O -- they love Google+ and are going full steam ahead with the social platform. We don't blame them, as we think with the right nurturing it can stand out among the rest. What's been sorely missing is options for third party applications to integrate with G+ as the do with Facebook and Twitter. Google has made that one step closer to reality today with the announcement of the upcoming Google+ API for Android and iOS. Based on the platform notes, supported out-of-the-box are Google+ sign-in, a share plug-in to share your app content to the G+ stream, +1 button integration, Google+ history functions, and a personalization feature, which will allow developers to pull in public G+ content and use it in their app.
It's not exactly perfect, but it's very close to what everyone was asking for. Now we just need to see the SDK and some apps built with it.
Source: Google+ Developers