Thanks, Mr./Ms./Dr. t.
From the very first time I started using WP, with Ecto as a front-end, everything posted correctly to the MySQL database. When the process failed, for no obvious reason (with 2.5), I created a folder within wp–content, uploaded images via FTP, and linked to that URL. A kludge, obviously, but it worked.
When I updated to 2.5.1, though, almost everything failed. Yes, I could created a text message within WP, and that showed up. Yes, I could upload images to the Gallery using the WP utility, and they were listed there. But they didn't show up.
I have everything archived, so I'm ready to start from scratch. I'll try 86ing the whole blog and database and trying again. But I'm nerdish enough to hate the idea of giving up without understanding the problem.
Anyhow, thanks much. I'll post a follow-up after my attempt as a draconian solution.