The Live SDK v5.0 was previously available as a preview version. The full release of the Live SDK v5.0 means we can expect to see a variety of third party applications integrating with single-sign-on, SkyDrive and other Live services.
Integration with SkyDrive could potentially be used to share data files between a PC and Phone version of the same app (e.g. like OneNote) or to provide a user accessible back-up, without having to build an app specific web service.
Here's how Microsoft describe the SDK:
The Live SDK contains the Live Connect APIs, which provide programmatic access to Live web services with a set of libraries that enables your apps to work with data in over 500 million user accounts in Windows Live ID, SkyDrive, Hotmail, and Windows Live Messenger. The Live SDK enables access to users’ identity profile info and allows your apps to:
- Easily personalize your users’ experience
- Take advantage of single sign-on scenarios using Windows Live ID in Windows Developer Preview
- Upload and download photos and documents in SkyDrive
- Create and update contacts, calendars, and events in Hotmail