Yes, but not an extension - code behind in the Theme solution.
Have a look at (our modified)
Artemia theme (originally) by
OneSoft.dk or one amended by
Antonio Chagoury adding some Twitter components.
We've extended this to provide an abstract of the Featured Post either as paragraph or as a float around the thumbnail image, third-column and two widget areas. We pull a YouTube thumbnail manually from YouTube so that you have a relevant thumbnail in your
Headline or Featured item summary. We had to extend the code-behind to support embedded media appearing as Featured or Headline articles.
The following is a work-in-progress customer site that we're also extending with ScrewTurnWiki and Gallery Server Pro.
Hope that helps.