The APStylebook.com has now redone its references to LGBT word usages. It no longer identifies "homosexual" as an acceptable term in reporting except in clinical studies and considers its use perjorative even then.
Personally, I've never liked the work "homosexual." It has a demeaning connation because of its use by the ultra-conservative right and bigoted derogatories. It's much like the n-word for African-Americans, sp**k for Puerto Rican-Americans, w*tb***k for Mexican-Americans, w*p for Italian-Americans, m*c for Irish-Americans, and the litany goes on and on.... It's also a very cold word.
As far as the word "gay" goes, it was used in the 1938 film Bringing Up Baby with Cary Grant and Katherine Hepburn. After Grant's clothes are soaked, Hepburn's character give him one of her satin/silk robes with ostrich feathers. When her aunt comes into the house, sees him, and gives him a look, he screams, "I've suddenly gone gay!" Did it get a laugh? Absolutely. And no one gave it a second thought. Of course, "gay" wasn't really a term that was frequently used in the 30's [It bacame more popular in the 70"s.] but it probably was the start.
Of course, we'll probably hear the wailing and gnashing of teeth from the right, but who cares?
link: glaad Media Releases
If you have never seen, Bringing Up Baby, it's a stitch and a classic Howard Hawks screw-ball comedy. Hepburn and Grant surpass themselves only in the Philadelphia Story.