This was posted on the playstation blog awhile ago. The developers made the announcment about the beta for psn+ members and those who recieved the voucher on the same day.
If you purchased the freshly released, and totally epic, God of War Saga, inside is a voucher for one free month of PlayStation Plus. There is a date listed for an exclusive God of War: Ascension Beta.
Looking at the voucher itself below, courtesy of TrendyGamers, you can plainly see the God of War: Ascension beta access kicks off on November 13th, 2012. Sony has yet to announce this information more formally on the PlayStation Blog, but this voucher is definitely official. It’s worth noting that there are those two pesky asterisks next to the date on the voucher, likely implying that the dates are subject to change. However, it seems you could at least expect the beta to launch—for PlayStation Plus members at the very least—some time before the end of the year.
Note: Article From Playstation Lifestyle
Wow that is such a long wait, just 1 week before PlayStation All-Stars come out, I guess I will only be playing this beta for a week.