From HTMLGoodies.com, parts two and three of their "PHP Tips & Tricks - A Picture Upload" series have been published.

• Part 2 - We now have the foundation of an image gallery with a web form to upload new images. But now we need to start making it a little more elegant. A more aesthetically pleasing approach is to have uniform thumbnails of all the images and list those. (requires the use of GD)
• Part 3 - The next feature to add to our picture upload application is to enforce some form of access control. [...] We do not want to let the world upload any image to our server, so we have to set about implementing a log in system.

As they wrap it up, you have a sample gallery that allows you to upload, (kind of) organize the photos, greate thumbnails automatically for them, and provide a method of access control to keep the unwanteds out...