Through the videos provided on this post, you will learn about the steps required to upgrade your version of WordPress to 2.7.
Chapter 1 of 7: Upgrade WordPress 2.6 to 2.7
Chapter 2 of 7: Backing Up My WordPress Database
Chapter 3 of 7: Download and Unzip the Latest Version
Chapter 4 of 7: Backup My WordPress Files
Chapter 5 of 7: Delete and Overwrite My Local WordPress Files
Chapter 6 of 7: Deleting Online WordPress Files and Upload
Chapter 7 of 7: Completing the Upgrade at “wp-admin”
 Chapter 1 of 7: Upgrade WordPress 2.6 to 2.7
Chapter 2 of 7: Backing Up My WordPress Database
Chapter 3 of 7: Download and Unzip the Latest Version
Chapter 4 of 7: Backup My WordPress Files
Chapter 5 of 7: Delete and Overwrite My Local WordPress Files
Chapter 6 of 7: Deleting Online WordPress Files and Uploading New Version
Chapter 7 of 7: Completing the Upgrade at “wp-admin”
(Tutorials courtesy of Scott Offord)