On the fields of Trenzalore, at the fall of the Eleventh, when no living creature may speak falsely or fail to give answer, a question will be asked. A question that must never, ever be answered.
In The Name of the Doctor the Doctor and Clara went to Trenzalore and it was revealed to be his grave. Was this the fulfilment of the prophecy which the Silence wanted to avoid?
On the fields of Trenzalore
Although I wouldn't describe it as a field - Check
at the fall of the Eleventh
Well, the Doctor didn't die - we also weren't given a reason to believe he wouldn't have any more regenerations. So was this where the 11th will fall? He did technically fall to the ground? You could also say he was defeated... Unsure
when no living creature may speak falsely or fail to give answer
But he did fail to answer - sure River answered but he didn't? However there was the spoiler at the end which implied River was with the Doctor, did she answer for him? Again, unsure.
a question will be asked. A question that must never, ever be answered
Now, this is the kicker. The Doctor's name was asked, however I suspect the question is actually slightly different... who was the "Doctor" we saw at the end?
The final point is idle speculation as we can't know until the the writers reveal it. However my question is this, was this the the fulfilment of the prophecy or are they going back to Trenzalore at some point in the future (before he dies)?