The first – and hopefully only! – Release Candidate of Ubuntu 9.10 Karmic Koala is released today, the 22nd of October.

beta111111
A release candidate is the final official “testing” version, and comes with potential to being the final version released bar any show-stopping bugs that might crop up between now and next Thursday.

Download
Grab your copy of the Karmic Release candidate from: –

http://releases.ubuntu.com/releases/9.10/ (Working)
Upgrade
If you’re already running Karmic beta then you pretty much have the Release Candidate (providing you’ve been keeping up-to-date with updates.)

Update your .iso to the release candidate

If you have a previous Ubuntu Karmic .iso lying around, instead of re-downloading the entire Release Candidate you can "update" your alpha or beta .iso to the RC using Zsync.
Zsync scans your existing .iso and only downloads the newer or updated "blocks". The result is a very, very quick way to get the RC!
Install zsync: sudo apt-get install zsync

Navigate to where you have your previous .iso saved
Rename it to the correct release candidate .iso name
(e.g. ubuntu-9.10-rc-netbook-remix-i386.iso )
Open a terminal and cd to the directory where the .iso is
Issue ‘zsync’ followed by the link to the release candidate ‘name.iso.zsync’ (see below)
Example
I renamed my netbook remix .iso from
  • ubuntu-9.10-beta-netbook-remix-i386.iso
to
  • ubuntu-9.10-rc-netbook-remix-i386.iso
I opened a terminal and navigated to the directory where i keep it.
  • cd /media/SharedSpace/Documents
and then typed: –
  • zsync http://releases.ubuntu.com/releases/9.10/ubuntu-9.10-rc-netbook-remix-i386.iso.zsync
It then scanned my "seed file" and updated the beta .iso to the release candidate .iso in under 5 minutes!
MAKE SURE YOU HAVE CORRECTLY RENAMED YOUR .ISO BEFORE SYNCING!
.zync list: –
Paste the corresponding url directly after the ‘zsync’ command.

http://releases.ubuntu.com/releases/9.10/ubuntu-9.10-rc-desktop-amd64.iso.zsync
http://releases.ubuntu.com/releases/9.10/ubuntu-9.10-rc-desktop-i386.iso.zsync
http://releases.ubuntu.com/releases/9.10/ubuntu-9.10-rc-netbook-remix-i386.iso.zsync