New 2.0 beta version of SWFObject is out (previously known as flashobject, then swfobject, then SWFFix project). Over the years, it become the de-facto standard for embedding Flash/Flex content in xhtml friendly cross browser compliant valid way.
The new version is a complete rewrite from SWFObject 1.5, so it needs to be tested like hell before officially launch because it will replace the older SWFObject and UFO scripts. And since they have Adobe involved, they will be including this embed system in the Adobe authoring tools in the future. GREAT NEWS! Meanwhile, grab the beta from google code.