You can find more details on the WordPress News blog.
In fact, Marilyn and I recommend you don’t! We like to wait for a while after a major release to give all the plugins time to catch up and make sure everything works. Jumping in blind on a client’s website is not what we do!
If you don’t currently have a maintenance agreement with us, don’t hesitate to contact us for one or for a project price to get your site updated and secure.
Anyone tackling the upgrade on their own should make a full backup of your site and database before beginning.