That's actually a really good question, and I went through the player and the website, and eventually called up Netflix to get their take on restricting some movies from the queue.
At this point, the Watch Instantly feature from Netflix will queue up only from the master account holder. This means that while you can choose the movies that go into the queue, you can't filter them with seperate profiles in the actual player. The same rules applied for a game station that also supports Netflix streaming.
However, I can appreciate your concern. What I've done in my house is queue up the children's movies, and doing so, I rank them #1 in queue each time it's a movie my kids are allowed to see, which places them at the front of the lineup. So essentially, I put all the "allowable" movies up front, and the "R" titles near the end. I don't mind scrolling past the kids titles to get to Die Hard (or other "grown up" titles) 60 titles down the line.
When you are finished watching the movies, you can also remove them from the queue, and they'll disappear.
I spoke with one of the managers at Netflix, and they said that your suggestion would be a great idea, but at this time, there's not a ratings safeguard implemented in their system, nor in the player.
I have a Samsung P3600 Blu-Ray player is there any way to have parental controls on the Netflix so that I can have movies and shows for me and my wife and stuff for my 4 yr old daughter in the cue at the same time?