Do you treat 17 year old stepchild like an adult?

Do you treat a 17-year-old like an adult? 

On facebook, I have a kids list set up so anything I post that I don't want kids to see (status message not appropriate to kids, a music video I don't want them to see, etc.), I exclude all the kids using my "kids list".  I don't have my 17-year-old stepchild on the kids list because her dad said that she's old enough now.  There are times when I wonder if that is ok from the standpoint of appropriate material but there is also the standpoint that her mother can log into her facebook (I would imagine she would know her children's passwords but I don't have verification that she does) and would be seeing this as well.  Not that she'd have much to say because my 14 year old stepson swears like a sailor and it seems to be just fine over there but just the thought of it...

Don't misunderstand - it's not like I am putting anything R-rated or more on my facebook because family is on there too but there are things that I'd just rather not have children see.  My stepdaughter is 17-1/2 now but I still cringe at viewing her entirely as an adult just yet. 

She doesn't want to be on the kids list (no big surprise there).  What 17-year-old wants to be included with the younger age group?