Just saw this in the Origin Client, in the Featured Today window. The T&Cs says it expires Wednesday, 3 September 2014 at 3 AM AEST.
Sorry, I couldn't see the sale on the Origin web site and I'm new to using Origin so can't provide a web link. View it from your Origin Client.
Edit: It seems some of you aren't seeing the Featured Today window. In the client click the Origin menu, and then select Launch Featured Today.