Really though, what kind of privacy would a ten year old need? I am now almost 15 and I have my own room, but I always shared a room until I was about 13 and then I got more social and needed more privacy.. I would probably be able to help you more if I knew what your son ( who is ten right?) needs privacy for. I will get back to you..........
I have an almost 10 year old and an almost 6 year old sharing a room...financial reasons and it was a quick move because the last place had mold and the landlord refused to fix (the worst of it was in the kids room). They have no problems other than fighting. As far as the privicy issued, i just make sure they know not to change when the other one is in there (one uses the bathroom one is changing in the room if they need to get dressed at the same time). They do a pretty good job as far as keeping things private. They do fight alot, this being summer my daughter is usually awake later and still up when my son goes to bed, so this can cause problems, but generaly it's ok. I shared a room with my brother, who was 3 years older when i was about 10 with no problems...i shared a room for about a year. We will soon have to move though, we also have a 2 year old who still sleeps with mommy and daddy, i'm trying to get her into her own bed, but i won't put her in the room with the other two, i'll wait untill we move then my son can have his own room (which he is dying for) and the 2 girls can share.
I find the biggest problem my kids have is the other child touching or playing with their things.
I don't know where you live but in most states here in the US there is a law that if the children are opposite sexes and over the age of 3 they are not allowed to sleep in the same room. I know, it sounds crazy, but it is actually a law. You may want to find out what the law is for the state you live in. Especially if you are going through a divorse, you don't want anything your ex can hold against you.