the latest trend in underground scenes. it's a method of storing files on an FTP server available to everyone. pub is short for public, as in a public access ftp site. whoever wants to build a pub finds an ftp site allowing anonymous read/write access and, without permission of the site op (or even the site ops knowledge), uploads whatever he wants on it (warez, mp3s, movies, porn, etc).

the advantages of a pub are anonymity and reduced risk of getting in trouble, i'd imagine. usually a pub's lifespan is quite short--the site op will notice a major increase in bandwidth usage, check the logs, and remove all of the content and/or disallow write access. deleters can also be a problem. another advantage is speed. often times a random pub will happen to be a T3 or above.

after a pub is built via user<>site or site<>site (FXP) transfers, the pub's IP address is usually posted on IRC or on a message board, along with the directory containing the files. directories are usually placed somewhere inconspicuous, like a log directory, and then inside of several other directories after that. often times several users will contribute, uploading their files to directories like "-=upped by PimpBot=-", etc.