The current version is still 2.3 (2004) and Ubuntu, like Debian, is based on that. At the Linux Foundation it is noted that

The FHS 3 specification is currently under development.

They aimed to release it by 1 July this year as this article describes, so the date you saw on wikipedia was merely this date they had earmarked. It hasn't actually been released yet at the time I am writing (12 September 2012). The changes haven't been decided fully, but there are some useful links in the link above (such as the fhs mailing-lists discussion and there is a discussion at lwn.net.

More details on the existing specifications are available at the Linux Foundation.

For more general information, two great questions on this site explain the filesystem hierarchy well:

• How to understand the Ubuntu file system layout?


• https://askubuntu.com/questions/165677/which-book-should-i-buy-to-learn-file-system-in-ubuntu