A couple of you have been having problems trying to upgrade to Ubuntu 10.10 from 10.04 LTS because the option to upgrade is not listed on in the Update Manager. This could be because, by default, update manager is not set to show this type of upgrade and to only show "long term support only" upgrades.
Simply launch Update Manager from the Admin menu, select go to settings and select the Update Tab. At the Bottom there is a drop down for "Release Upgrade: show new distribution releases" Change to Normal Releases and rerun the check. The 10.10 option will now show.