JKR on the Today show:
Harry and Ron are Aurors who have/are going to revolutionise the Auror Office.
Hermione plays some kind of role in the Department of Magical Law Enforcement.
(JKR also said that Snape isn't a "hero", which I personally agree with but I know many of you won't)
In light of the "oh, but the epilogue leaves things so wide open!" jubilation, I believe this calls for a poll.
It's canon that Harry and Ron are Aurors, and that Hermione works for the Department of Magical Law Enforcement.
Yes. JKR said it, and it's factual information about her characters, not opinion. Therefore, it's canon.
No. It's not in the book. Therefore it's not canon.
It's not canon at the moment, because it's not in the book, but it will become canon when JKR publishes it in the HP Encyclopaedia.
I'm not counting that "I don't think he's a hero" bit because while some believe JKR's interpretation trumps all others, I think her moral compass is often bewildering. In other words, if you think JKR's opinions of her characters are a part of HP canon, good for you, but not everyone thinks so.
There are more interviews coming this week, where I'm sure we're going to find out all sorts of things that are true at the time of the epilogue. My only real question would be why she didn't put them IN the epilogue. I'm over the moon knowing what Harry does for a living, but why couldn't I read it in the book? WHICH IS SUPPOSED TO BE ABOUT HARRY, NOT RANDOM KIDS WE'VE NEVER MET BEFORE. :|
Oh, ETA: MSNBC article on the epilogue, where JKR explains that the epilogue was supposed to be "poetic". AHAHAHAHAHA. Well, you failed there, Jo, but A for effort!
The MSNBC article also shows promise for the Neville/Luna ship, which she flatly shot down in another interview years ago. lol, JKR, make up your mind.