When you click the "Browse..." button beside a file upload field, if that
field was empty, then the "File Upload" file browser that appears defaults
to the user's home directory, regardless of that last directory you were in
when you last selected a file to upload.  If the upload field already
contains a filename in a specific directory, then the "File Upload" dialog
does go to the directory containg that file, but it doesn't go to the last
one if the field was blank.

The "File Upload" dialog should return to the directory you were browsing
when you last chose a file to upload.  This is the behaviour in Internet
Explorer, Netscape 4.x, and Mozilla.

This is very annoying when I have a form that asks for a bunch of files
from the same directory to be uploaded at one time, which is very common in
such web applications as:
 - message boards that allow you to upload multiple images in a message
(e.g., sfs 1.0 - though that app isn't distributed on the Web yet, but I'm
sure there are others);
 - remote file management apps that support uploading multiple files at a
time (such as the one included in CPanel 4, a common tool for administering
a website through a browser).