Wired has this article about J.K. Rowling outing Dumbledore as being gay. From the article:

She was asked by one young fan whether Dumbledore finds “true love.”

“Dumbledore is gay,” the author responded to gasps and applause.

She then explained that Dumbledore was smitten with rival Gellert
Grindelwald, whom he defeated long ago in a battle between good and bad
wizards.

This page has a list of 7 clues that Dumbledore was gay including:

1. His pet. “Fawkes, the many-colored phoenix, is ‘flaming.'”

2. His name. “While the anagram to ‘Tom Marvolo Riddle’ is ‘I am Lord Voldemort,’ as my good friend pointed out, ‘Albus Dumbledore’ becomes ‘Male bods rule, bud!'”