JabRef

http://jabref.sourceforge.net/
JabRef is an open source bibliography reference manager. The native file format used by JabRef is BibTeX, the standard LaTeX bibliography format. JabRef runs on the Java VM (version 1.5 or newer), and should work equally well on Windows, Linux and Mac OS X.
note from ANU Data Management : Endnote does [...]

Mendeley

http://www.mendeley.com
Mendeley is a free social software for managing and sharing research papers – and it’s also a Web 2.0 site for discovering research trends and connecting to like-minded academics. We’ve just launched into public beta.
http://www.mendeley.com

There is more detailed background info on our blog
(http://www.mendeley.com/blog).

RefWorks improves service with new features and enhancements

RefWorks, the research tools arm of ProQuest, has announced the latest release of features and enhancements to its web-based research management, writing and collaboration service for the academic and research communities. Users can now further their research and collaboration efforts by learning more about authors through the new Author Linking feature. [...]

Zotero

http://www.zotero.org/
not new, but contining to improve and worth investigating as an alternative to Endnote.The home page links to a demo and an introductory guide.

Zotero is an easy-to-use yet powerful research tool that helps you gather, organize, and analyze sources (citations, full texts, web pages, images, and other objects), and lets you share the results of [...]

RefWorks Announces August 2008 Release

During the week of August 11-15, 2008, RefWorks is scheduled to release another feature upgrade to the program. As in prior releases, most of the new features and enhancements will be available instantly to all registered users without the need to download any upgrade programs. A notice of the August release, [...]