A metapost is a collection of six or more posts on a specific topic. When there are as few as six posts, the metapost may simply string cite them. As the number of posts increases, it is more likely that they are organized in some way.
The step beyond metaposts, which only give the date and thumbnail description of the prior posts, is a Metapost Plus, which provides the entire prior post, organizes all of the posts, and comments on the package, such as with recommendations. To see what is available as a Metapost Plus, visit my blog and look on the left side box, under my bio.