And since that slip, Brandon has treated it as 'revealed' and mentionned it once or twice, apparently anyway (there's somewhat of a doubt about those reports - at the Q&A with him I attended, Brandon really striked me as a hardcore spoiler-free sort of guy that even if he made a slip once wouldn't go and repeat it to other audiences later).

But yeah, that Farstrider is Noal is confirmed, and was sort of obvious for a few books. The name, the stories etc. With KoD and the embarassed 'he's my cousin' lie, the opening quote from the KC translated by him combined with the verse he remembered about Mat it was sort of painfully obvious!