I probably should add a tutorial content type already.
Okay, I was having problems with a new gallery2 install not rotating resized images correctly. I didn't have the correct software installed on my system, and gallery2 really isn't supported on Ubuntu systems later than, say, 2007, so, this install is a less than desirable configuration in many ways. I really can't stand Gallery3, and dislike the style of focusing on a single photo, leaving a photo stream as a second class citizen, of other gallery packages I tested, so back to the somewhat bloated world of gallery2.
Which wasn't quite working. No rotating.
Blah blah blah. The fix:
$ sudo apt-get install libjpeg-progs
It'll likely be version 8d.