This Plugin removes all content before the tag when viewing the post by itself, but shows that text on multi-post pages.
The tag is the opposite of the tag. Where the tag hides all content that follows it when viewing the post on multi-post pages, the tag shows content preceding the tag when viewing the post on multi-post pages and hides that content (with the exception of a
p> if necessary) when viewing the whole post. This gives a way of adding content for an excerpt in the Visual Editor without having to use the Excerpt box. When used in conjunction with the tag, it gives greater flexiblity to create an dynamic excerpt without having to repeat content in the Excerpt box.
Note on "Requires at least": The Visual Editor button works with TinyMCE version 3.x, which is in WordPress 2.5. So the main functionality may work in previous versions, but the tag will have to be manually entered in the Code Editor.