Very detailed read:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnnetserv/html/AzManApps.asp
On a related note, I can recommend Keith's roadmap article for the big picture:
http://msdn.microsoft.com/security/identityaccess/default.aspx?pull=/library/en-us/dnnetserv/html/DotNetIdM.asp