The platform has been opened up for early developer preview and will allow for the following features:
- Sign In With Google+
- Share Plugin
- Mobile +1′s
- Google+ History API
- Google+ API
“In fact, there are now more people that use Google+ from a mobile device than from a desktop computer”
The platform includes mobile web plugins as well as Google+ SDK for iOS with an Android SDK coming soon.
See the Google+ Developers Blog for more information.