Ebay will allow users to use blog, wiki and tagging technologies to help users sell their stuff. Sarah Houghton, over at the Librarian In Black blog, has been posting some good information on tagging and how it will affect our jobs as librarians. In "Subject Headings vs. Tagging" she says that she believes that in 30 years or so, subject headings will be far less common than tags for finding content.
If you need more info about tagging click here: http://www.librarything.com/about.php
Source: Library Journal Tech Blog