A voice from Microsoft confirmed that the Exam 70-323 is not obligatory any more. At the end of August, it will be added the exam 70-324, which is the “light version” of 70-323. It is especially developed for small businesses and it will not have complex questions about hybrid and big enterprise environments.
I suggest you, that if you are interested in doing this exam, to join Jump Start.
More on: http://blogs.msdn.com/b/mssmallbiz/archive/2012/08/07/announcing-the-administering-office-365-for-small-businesses-jump-start-for-the-74-324-exam.aspx.