That was easy.
I followed the upgrade instructions here, making sure to back up the databases as described here.
I waited a bit before I did it, wanting to make sure gurus like MacManX gave it the OK. Then I wanted to wait until I had a free afternoon to work on it. Wouldn’t do if I corrupted the database or destroyed all my files or something and then had to run out and do the swim team carpool.
So far, everything looks good. Thanks to all the WordPress people for working so hard on it!