I didn’t hear big announcement of it, but deep in the docs (? PHP 5.1.0) you’ll find a note about additional Libxml parameters. In there you’ll learn about “LIBXML_NOCDATA,” and it works like this:
simplexml_load_string($xmlraw, 'SimpleXMLElement', LIBXML_NOCDATA);
Without that option (and with all previous versions of PHP/SimpleXML), SimpleXML just ignores any < ![CDATA[...]]> ‘escaped’ content, such as you’ll find in most every blog feed.