After Pavonis's posts, I just want to say that while I don't have a problem with spoilers, I do understand why others might. While I don't mind ruining stuff for myself, I really do think it is rude for people who do know to ruin it for people who don't. My general rule is if it is something that I was curious about going in, or something that surprises me when I learn it, then it's a spoiler and I'll code.
It is the responsibility of the people who know something spoilery not to ruin it for others. I think as long as you warn people about spoilers, either by spoiler coding it, or saying "this is a spoiler" then you are covered.