I couldn't find any way of figuring out what the folder names mean and how things are organized in them. On my iPhone there are actually 28 randomly named folders in my DCIM folder when I connect my iPhone to my work PC. On my Mac, the Photos and ImageCapture apps somehow know how to manage those folders.
The only way I could find to easily locate an image while on my PC is to do the following:
1) Connect your iPhone to the PC
2) Open the "Internal Storage" (i.e., iPhone looks like a memory stick to the PC) in Windows Explorer
3) Open the "DCIM" folder
4) In the "Search" box at the top right (or where ever it's located in your flavor of Windows) type "*.jpg".
5) Voila ! you have a list of all the images in DCIM. You can display the search results as a list or thumbnail icons. In "Details" view, you can sort them by "Name" or "Date Modified" to easily locate the image you want.
A word of caution - I wouldn't move the images from one folder to another. If you do, this may impact how your Mac OS X manages images.
