Welcome to Hardy Heron Alpha-5, which will in time become Ubuntu 8.04.
Pre-releases of Hardy 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.
Alpha 5 is the fifth in a series of milestone CD images that will be released throughout the Hardy development cycle. The Alpha images are known to be reasonably free of showstopper CD build or installer bugs, while representing a very recent snapshot of Hardy. You can download it here: http://cdimage.ubuntu.com/releases/hardy/alpha-5/
(Ubuntu JeOS) http://cdimage.ubuntu.com/xubuntu/releases/hardy/alpha-5/
for a list of mirrors.
Alpha 5 includes several new features that are ready for large-scale testing. Please refer to http://www.ubuntu.com/testing/hardy/alpha5
for information on changes in Ubuntu and https://wiki.kubuntu.org/HardyHeron/Alpha5/Kubuntu
for changes in Kubuntu.
This is quite an early set of images, so you should expect some bugs. For a list of known bugs (that you don't need to report if you encounter), please see: http://www.ubuntu.com/testing/hardy/alpha5
If you're interested in following the changes as we further develop Hardy, have a look at the hardy-changes mailing list: http://lists.ubuntu.com/mailman/listinfo/hardy-changes
We also suggest that you subscribe to the ubuntu-devel-announce list if you're interested in following Ubuntu development. This is a low-traffic list (a few posts a week) carrying announcements of approved specifications, policy changes, alpha releases, and other interesting events. http://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-announce
Bug reports should go to the Ubuntu bug tracker: https://bugs.launchpad.net/ubuntu