Joel Spolsky and Peter Thiel. I didn't find out they were gay for a long time, though I guess it just shows that it's not/shouldn't be anything remarkable.
Joel was a real, honest-to-goodness role model for me when I was 18 and still wondering whether tech was a place where you could comfortably work as an out gay person.
He doesn't seem to do much in the way of gay activism -- his blog bio used to mention his partner by name, but it's been dropped. I sort of wish he'd do more, but on the other hand, his quiet, unassuming but unabashed acknowledgement of his sexuality is really the ideal I feel we should be aiming for.
Me, I overcompensate, but that's because I'm still angry about high school :-) It gets better, kids!