A popular feature of most news sites this days is to display a thumbnail based on an image from an article (usually the first image) in the article's teaser (first few lines) and then have the full sized image displayed when the entire article is opened after the "read more" link is clicked.
How can this be implemented in WordPress?
P.S. I tried this using the "Post Thumbnail images" feature. However the result was not desirable. The problem was that the large image was the first item in the post and was floated left. This meant that both the full sized image and the thumbnail were being displayed in the teaser.
What I want is to display only the thumbnail in the teaser and the large image in the full article.