The creator of
Haiku Podcast has made a very nice video presenting
Haiku OS, a BeOS-like Free Operating System which is now mostly in alpha stage and can already be used for simple things. This video shows that it's well on its way and I believe it has great potential as a possible future contender in the realm of Free Operating Systems, as they start developing some more exciting things based on the first release of Haiku. Here's the video:
http://sikosis.com.nyud.net:8080/haiku/Haiku05.divx