In theory you can upgrade Ubuntu Edgy to Feisty Herd 3 right now by typing gksu update-manager -c -d or sudo update-manager -c -d on the command line. (Insert standard disclaimer here about how Feisty is alpha software and may fuck up your life.) This gives you the normal Software Update window with the addition of a “Distribution upgrade” option. However, on one of my test machines, the distribution upgrade failed with this error:
Authentication failed
Authenticating the upgrade failed. There may be a problem with the network or with the server.
On the command line I saw an error message like this:
extracting ‘/tmp/tmpVuEU0n/feisty.tar.gz’
authenticate ‘/tmp/tmpVuEU0n/feisty.tar.gz’ against ‘/tmp/tmpVuEU0n/feisty.tar.gz.gpg’
exception from gpg: GnuPG exited non-zero, with code 131072
The solution is to run gpg once, as a normal user, and let it create its configuration files and keyrings. Once it says Go ahead and type your message …, you can just press Ctrl-C to get back to the command prompt, then run sudo update-manager -c -d again.
This is Ubuntu bug 78673.

