Links to "user" photos did not work after updating from Moodle 1.8 to Moodle 1.9.
However, I noticed the link works on moodle.og
I wonder if some code has been changed since moodle.org updated from 1.8 to 1.9 that may have cause this problem.
I've attached an image that helps show the problem.
This is a new install Moodle. 1.9 (March 16 or 17, 2008 version.)
I installed it in a new directory, then set my config.php file to use a copy of the "moodledata" folder.
I noticed that now in the moodledata folder, there is a "user" folder using a new folder structure and the older "users" folder, which I assume is perhaps just a backup of the data.