But if you can't wait for the official release for the Chromium 11 for Ubuntu... then the packages are already in this Stable Chromium PPA channel. If you subscribe to this channel, you'll receive the updates when the official channel for Chromium 11 is released automatically.
Before you're using the "Stable PPA"...
The developers advice you to completely remove the current daily added stable PPA channel (if it's something other than this PPA) and downgrade Chromium using this PPA (you can read more information from the above link).
The Chromium 11 also bring few major features such as the ability to completely remove adobe flash videos cache from your web browser easily via the usual "clear browsing data" command + many more bug fixes as well.