Yes! And by the way, I am not ashamed to admit my love of The Notebook. While it isn't the best thing Ryan Gosling has done, it was the best part of a terrible blind date.
I'm 27, and I grew up in a small Ohio town (1,100 people) with a large Italian-American and rural farmer population. I can honestly say that I grew up knowing 0 LGBT people until I got to college in 2006. When Brokeback Mountain came out, I was 16 and at the height of a proto-masculine nerd persona that I was trying to portray to people. I always knew that I was a bisexual man, but I never acknowledged it as a reality. While Brokeback Mountain was a turning point culturally, bringing out the worst in and enlightening many, I can't say that it changed my life. What it did do was get people talking about homosexuality more, and I was able to see that not every person was hateful and bigoted - much of the problem was ignorance. I now had that one code/qualifier movie to see if I was going to find someone I wanted to spend time with. "Have you seen Brokeback Mountain?" would immediately bring out a person's feelings about homosexuality (and of course film) in my later high school and early college years. That alone makes this an important film worthy of the Canon as well as show how fantastic the four principle actors are as well.