IMDB quotes the following from Arena Magazine's Star Wars Issue:

Star Wars actor Hayden Christensen has lost himself a potentially devoted fanbase by laughing off suggestions that he's gay. A leading American gay magazine declared Christensen to be "definitely gay", and Hayden's more amused than annoyed at the speculation. He says, "It's hilarious. I'm not gay. It's amazing how much people will speculate if they haven't actual information to draw from, they just make up whatever they feel is appropriate. "That's cool. As long as the people I know and care about know the truth then everyone else's opinion doesn't really matter." Cast and crew on the set of the upcoming Attack Of The Clones film know where the 20-year-old's tastes lie - he often forced extra takes of his kissing scenes with stunning co-star Natalie Portman by turning to the camera grinning and flashing a thumbs-up. He laughs, "They would be like, 'You have to stop doing that Hayden! Now we have to do the whole scene again.' I'd be like, 'Fine'."

Thanks to Maurice for the alert!