GHacks.net posted a guide about upgrading Ubuntu from 10.04 to 10.10

If you are currently using Ubuntu 10.04 and are interested in 10.10 you have choices – you can burn yourself an ISO and do a complete, fresh installation, OR you can upgrade using apt-get without having to bother with a re-installation. Of course I should warn you that, as of this writing, Ubuntu 10.10 is still in beta. That doesn’t mean you have to avoid the upgrade. It does, however, mean you run the risk of not everything working correctly. But if you are all-too-antsy to get that precious 10.10 on your machine…the task is actually quite simple.

  Upgrade Ubuntu from 10.04 to 10.10