The next release of Ubuntu code named Karmic Koala will be on the 29 of October. You can pre-order your free CD now. All you have to do is to head here and log in with your Launchpad account (you can easily create one if you do not have already).
When Karmic finally releases, you will be sent a copy on CD free of charge. Depending on where you are, the CD can take between 2 to 6 weeks to arrive. So if you do not have a fast Internet connection and want to get the latest from Canonical, then you’d better put in that request now.