arXiv.org was developed by Paul Ginsparg in 1991
It was hosted by Los Alamos National Laboratory and was called the LANL preprint archive and it URL was xxx.lanl.gov
It is now hosted by Cornell University Library
arXiv has developed a Facebook app called myarXiv but at present you are required to opt-in and create a public author identifier to use this service
Getting started on arXiv.org
arXiv acccepts submissions in a variety of file formats. These include PDF, TeX, and LaTeX. A new user needs an endorsement from a current user before they are allowed to submit material.
In most cases, the author retains the copyright to the material uploaded. The remaining material is usually either in the public domain or is covered by a type of share-alike license. This will be indicated by a statement attached to the material.
Paul Ginsparg reviews the history of the e-print repository and its role in fostering scholarly communication.
A presentation, on SlideServe, by Ginsparg on how to identify the resources to maintain a repository like arXiv.