Interesting topic. I'm sitting here trying to recollect some recent books I've read where genders were blatantly inauthentic stereotypes. And honestly, I don't notice it that often.
Only one book comes to mind (which I won't mention here for fear of a beating, but I reviewed it on my blog if you're interested) and in that one, it was the male characters who were poorly-written (every male character exactly the same - no variation). Actually, the whole damn thing was poorly-written, but reflecting on it, character development was a big thing.
Point being, I'm not sure it's something to worry about too much.

I agree that it's about writing a character, a person, versus focusing too much on gender. My current WIP (Novel X) stars a female lead and I'm not finding a need to change how I develop her character versus how I'd develop any other character, though I'll admit I used to be horrible at stereotyping. For Novel X, I find the biggest struggle is writing her perceptions and relationships with men (not sex, just general interaction). Specifically, what's going through her head sometimes. Hopefully I'm not getting in the way too much.

Good luck with this and great topic. The responses here have taught me a great deal.