not if the document has an existing <textarea> (and thus </textarea>). <plaintext> is rather final ... see here for a demo I just threw together: http://getpostdelete.com/plaintext.html

The HTML interpreter packs up its bags and goes home - you can't "close" a <plaintext> tag if it's existing in a plain HTML page.

However, you can still manipulate it through the DOM.

Yeah I sort of realised that as I said it. Hmm.