I tried to use a CDATA section when editing a new post. e.g.
Blah blah blah.
<![CDATA[some text that includes various unescaped less than signs < ]]>
blah blah.
WordPress made a hash out of this. It neither completely stripped the CDATA section delimiters nor left them intact. It added a space after the less than sign that begins the CDATA section.
This looks like intentional behavior, but it strikes me as a bug. I should be able to use CDATA sections when editing, but if they are removed, they should be removed in toto and their contents escaped.