Known issues with the [[plugins/comments]] plugin:

* There is some common code cargo-culted from other plugins (notably inline and editpage) which
  should probably be shared
* Previews always say "unknown IP address"
* Add `COMMENTOPENID`: the authenticated/verified user name, if and only if it was an OpenID
* The default template should have a (?) icon next to unauthenticated users (with the IP address
  as title) and an OpenID icon next to OpenIDs
* Should the comments be visually set off more from the page above?
  Rather than just a horizontal rule, I'm thinking put the comments
  in a box like is used for inlined pages.
* Instead of just a link to add a comment, it could have a form to enter
  the title, similar to the form for adding a new blog post.