This link was passed on to me today by Writer Beware. It's not about anything to "beware" of, but is a fantastic article about what subtext is in a story, and how to bring it into use for yourselves. The part I found most illuminating was how David Baboulene linked the idea of subtext with that of an imbalance of knowledge between character and reader (either the reader knows more than the character does, or less, or both!).
Everyone should read this one!