Here in the generla MS Office Blog you can find most of the Office 365 news.

In November 2013 MS introduced message encryption for Office 365 messages:
http://windowsitpro.com/blog/office-365-message-encryption-protect-your-email-against-spooks
http://blogs.office.com/b/office365tech/archive/2013/11/21/introducing-office-365-message-encryption-send-encrypted-emails-to-anyone.aspx

Office 365 External Sharing improvements: read sharepointpromag entry