With Windows Azure AD Rights Management, you can protect your data by encrypting and managing access rights, including Office documents, Exchange email, and SharePoint document libraries across your Office 365 Enterprise Preview services and applications.
The technology is highly integrated into Office 2013 Preview, Exchange Online Preview, and SharePoint Online Preview, and offers a seamless experience for both end users and administrators in document authoring, email, and SharePoint publishing.
All you have to do to get started is:
Read all the details in this blog post "Enabling Windows Azure AD Rights Management in Office 365 Enterprise Preview" from the AD RMS Team Blog.
See also