I posted this as a comment at Mother Tongue Annoyances, but it's (a) tied up waiting for moderation, and (b) slightly messy there, so I'm copying and pasting here. I've also tidied it a little - the ability to preview here lets me get it a bit neater

Phil Plait manages to clearly indicate when he's making corrections, through not relying solely on overstriking.

I do the same: If I have an update, it will be labelled as an update. In addition, my CMS has a "Revisions" feature, which allows users to look at the history of the post and see every revision I've made (this may not be enabled for anonymous users, but it's easy enough to register).

In short, to answer your direct questions:

  • <del/> isn't a neccessary way to indicate deletion or correction - there are alternatives, many of them clearer
  • <del/> isn't a sufficient way to indicate deletion or correction. You're going to have to provide other information to show what the new text is, why you changed your mind, etc - and this extra information will show that there was a correction or deletion.

    To address a couple of other problems with your post:

    • <del/> is not the same as overstrike. The w3c definition of the tag states:
      User agents should render inserted and deleted text in ways that make the change obvious. For instance, inserted text may appear in a special font, deleted text may not be shown at all or be shown as struck-through or with special markings, etc.

      . Strike-through is one way that <del/> might be displayed, it's not the only way.

    • overstrike is not the same as <del/>. If you want to guarantee your text is displayed with an overstrike, you'd use <strike>; This is, in fact, what I use whenever I'm making changes of the sort that you describe as "crying wolf". You should *not* assume that just because you see overstriking that the author was mis-using the <del/> tag - it's far more likely they were using the <strike/> tag.
    • Using overstrike is a continuation of a tradition of using things-that-resemble-deletion-but-aren't to indicate humour - cf The Jargon File talks about a much earlier incarnation of this.

    In short, your confusion between <del/> and <strike/> is another data point in favor of seperating display information (like, overstrike?) from metadata (like, heading type, deleted/inserted, etc).