Later this week Episode VII will be in cinemas; this has the potential to revitalize Star Wars (or not, but that's not the issue here). It'd be a shame if someone carelessly posted spoilers and ruined that for someone (not everyone will be able or willing to watch it at midnight (I'm sure some people are thinking it but I'm not talking about me, I will be watching the first showing)).
My plea is that, for some time after the release, everyone marks everything related to it with spoiler tags like these:
Darth Vader is Luke's father
The option is in the bar above the text window, to the left of the font selection, it's one of the "Special BBCode" options (condescension over).