The next preview release of Azure AD Connect is out and available. If you don't know what that is, it's a replacement solution for DirSync, the tool that synchronizes your organization's AD information with Azure AD. Azure AD is the back end identity store for Office 365, CRM Online, Azure and so much more. This new version supports an in place upgrade from DirSync, attribute filtering by service, multiple forests and more. There is also a new "Pilot" mode that would let you test it out for a sub group of your directory before converting everything over.
To learn more and find a link to the download, read this Active Directory Team Blog post: http://blogs.technet.com/b/ad/archive/2015/03/24/azure-ad-connect-preview-2-is-available.aspx