That slot on a Polaroid camera was actually an edge connector. The flash bar was printed on a PCB and had gold trace "fingers" on a protruding section, like an ISA card. These are very cheap, as only one side of the connector even is a connector at all, the other is just a PCB. But they also aren't physically very strong and aren't good for a lot of insertion/removal cycles.
The iPod 30-pin has a metal shelled connector on both mating pieces. These are more precise, last longer and with the a latch system (present on some iPod cables, not others) physically strong. You can hang an iPod Mini easily from a latched 30-pin connector while the Polaroid flash bars fell out without even putting weight on them.
Also note Steve Jobs didn't design Apple's 30-pin connector, Donald J Novotney did.
Interesting update - thanks very much for the info