Update at Rowling's site
She's updated the rumors page, and the following can be found there:
Dumbledore is really Ron/Harry 'from the future'
Your inventiveness knows no bounds, and I do not mean that sarcastically; these theories open up exhilarating new vistas of possibility...but they're wrong. Could it be that by speculating that Harry/Ron becomes Dumbledore, you are seeking reassurance that neither dies young?
I've also heard a whisper about Ron and Hermione's son time-travelling, so I shall go further and tell you that NONE of the characters in the books has returned from the future. As for the idea of Ron and Hermione having a son...(chuckles as the distant roars of a million shippers reach my ears, all cursing me to an eternity of unsatisfied curiosity).
Nicoloas Flamel is going to come to Hogwarts to teach postions
Flamel has now died; Dumbledore explained in the 'Philosopher's Stone' that his old friend was going to choose death rather than allow his stone to fall into the wrong hands.
Colin and Dennis Creevey will be the new Gryffindor Beaters
Nice idea, but no. The new Gryffindor Beaters will be completely new finds of the new Captain's.
There will be a chapter in Half-Blood Prince called 'Lupin's Papers'
I've already answered this in FAQs, but as this rumour is still cropping up in fan letters I thought I'd reiterate here that there will be NO chapter called 'Lupin's Papers' in book six, nor will there be chapters entitled 'Pettigrew's Pamphlets,''Sirius's Circulars' or 'the Pocket Crosswords of Severus Snape'.
Let me remind you once again that any 'information' about the contents of 'Half-Blood Prince' should be treated with extreme scepticism unless it comes from this website or from my publishers or agency. The silly season is upon us; there's bound to be an 'inside leak', ie, total fabrication any time now.

She's also managed to update her About the Books section in FAQ as well. Sorry, I ran out of time to type. ;) Be sure to stop by her site to check it out.