I had never attended a funeral prior to my aunt's last year while on vacation in the Philipines. I probably wouldn't take pictures if I attended at home in the US but I know that in the Philippines, it's definitely ok to take pictures. Heck, people even videotape for relatives that can't make it or for remembrance.
I'd always seen open casket pictures that our relatives would send us of from some family member's funeral and it always seemed a bit macabre to me but to actually experience it (see it) in person is definitely another thing.
My cousins asked me to take pictures when I attended their mother's funeral. I wasn't exactly sure how/what I should shoot so I came up with images like this:
That's one of my cousins giving her mother a final goodbye. You can see there is a guy there videotaping the whole thing.
It did seem odd, for me, to take pics with so much raw grief going on in front of the lens. I couldn't help but tear up as I was shooting the entire time. In the end, my cousins were very grateful to have the pictures I took of them, even in their extreme grief.