Starting today, WordPress 4.0, a.k.a. “Benny“, is available for download or to update your 3.x website.
As I told my WordPress clients today:
If you login to your WordPress Admin today you will see a notice saying WordPress 4.0 has been released. The most recent version of WP is 3.2. As you may know, this is a major update. Minor updates, like from 3.1 to 3.2 are for security and other functional updates. But a change from 3.x to 4.0 has major changes that may effect how your theme and plugins work.
I strongly recommend you wait at least a week before doing this update (this gives plugin developers time to find and fix plugin problems). Before you attempt the update, make a FULL BACKUP. Only then attempt to update core WP.
If you run into any problems or if you would like me to do this for you, just let me know.
Here is another article that summarizes the changes:
Let me know if you need any assistance with your WordPress website update!