Evil story - I was using my digital camera the other night, and I was curious, so I took a look around my 16MB Compact Flash card. I noticed that it was formatted FAT. So I was going to format it to something else. I would have preferred UCF or something, but my Mac wouldn't write a UCF filesystem. So I went ahead and formatted my Flash card as HFS+.
Wouldn't ya know it - next time I turned my camera (a Nikon Coolpix 4300) on, it complained that the memory card had not been formatted, and could not store any pictures until it had been formatted. And now we are back to FAT again.
What Operating System does your digital camera run? This is the kind of question nobody asks, but perhaps somebody should. Nikon's camera navigation system seems to be "running" Windows...