The Joomla! project has released version 3.0.1 which is a security release for the newly released Joomla! 3. As there was a small error in the update code, you will need to install a patch before doing the update to Joomla! 3.0.1. There are more details available at http://www.joomla.org/announcements/release-news/5468-joomla-3-0-1-released.html.
