The latest development milestone release (Herd 5) for the Ubuntu project’s next release, Feisty Fawn, has been released. This release will become Ubuntu 7.04 on April 19th 2007.
Pre-releases of Feisty are not encouraged for anyone needing a stable system, or anyone who is not comfortable running into occasional, even frequent breakage. They are however recommended for Ubuntu developers and those who want to help in testing, reporting, and fixing bugs. Installing a milestone and then upgrading through the release cycle should leave you with a close approximation of the final release.
Herd 5 is the fifth (and last one before the beta version) in a series of milestone CD images that will be released throughout the Feisty development cycle. The Herd images are known to be reasonably free of showstopper CD build or installer bugs, while representing current snapshots of Feisty.
The primary focus during the time from Herd 4 has been bug fixing. Please refer to this link for information on changes in Ubuntu, and this link for changes in Kubuntu.
You can read the complete release announcement which also contains links to the mirrors where you can get Herd 5.