When your projects include SWF files created with Adobe Flash or Flex, the newly updated Insert Flash feature in Dreamweaver, which now uses the open source SWFObject 2.0 codebase, enables you to visually preview your SWF file in context using Live Preview and even design the static, alternative HTML/CSS content right in Design view, too.
The thing that struck me most here was that SWFObject 2 will be used as the default for embedding Flash content in HTML pages, which is very cool. For those who don't know, Adobe has always rolled their own embedding code which was cumbersome at best. Every developer I know would end up creating their own HTML files and using SWFObject to embed Flash - in essence redoing what Dreamweaver had already done for them, albeit poorly. It is nice to see Adobe yet again making great use of the open source contributions of the community.
What is more exciting to me, however, is that one can assume Flash CS4 and the next version of Flex (either Flex 4, or an update to Flex 3) will use SWFObject to embed the SWFs they publish as well. A quick search of the SWFObject Google Group confirms this as well.