So Dumbledor is gay...

To clarify my last statement, and this is just what I think, no actual proof, I don't believe she just made up the fact that he was gay after the fact to make some point. I think she always intended him to be gay, but possibly due to pressure from her publisher decided to keep it out of the books so the rightwingers--who already had enough to gripe about with witchcraft and death and the like--wouldn't crucify her. Then after they were all written, when someone asked her a direct question about the character, she decided there was no harm in revealing it now. I understand that, and I can't really imagine the kind of pressure best-selling authors must get from their publishers, but it does bug me she didn't feel freer to state ti more directly in the books, especially the last one where it would have fit the most organically.

Long story short--much too late--the great thing is that you dont' have to read the books as the character being gay becasue ultimately it doesn't matter. Just as in real life, a person's sexual orientation is one of the least interesting things about them.

She didn't make it up to make a statement. This is from when they filmed Half-blood Prince:

J.K. Rowling read through the script for this film, and found a line where Dumbledore mentions a girl he had a crush on when he was younger. After reading it, she informed the filmmakers that Dumbledore is in fact gay, and that his only romantic infatuation was with the wizard Grindelwald, whom he later had to defeat in a wizard duel. She later made this information public while promoting the final book, Harry Potter and the Deathly Hallows.

So she's known all along.