Heres the latest news from the PSN Team:

Hi guys,
Some of you keen eyed consumers have noticed we made a bit of a boo-boo for Assassin’s Creed Revelations weekend deal. PlayStation Plus users weren’t able to get the discounted prices as advertised, so apologies for this.
The good news is that the offer will now be available (properly!) until Wednesday 13th June. Whether you are a PS Plus member or not, the offer is available to all!
If you are PS Plus member and went ahead and purchased the game without the discount please contact customer services here for more information.