Forum:Spoiler Expiration

How long does a piece of information remain a spoiler? When does a plot detail just become a part of the background story? I've noticed that Wikipedia policy discourages the use of spoiler warnings because it's generally expected that article subjects will be covered in detail. Don't get me wrong, I think a warning makes sense for unreleased content... but at what point does a plot overview just become a plot overview? -- Karm1c 21:37, February 17, 2010 (UTC)