Actually, there is a region lockout of sorts, but the main difference is PAL and NTSC (Japan & US have the same region chip).
http://en.wikipedia.org/wiki/Super_Nintendo_Entertainment_System#Regional_lockout
I have a Pro Action Replay for SNES and it has 2 slots for the purpose of bypassing region lockouts. One for the cartridge to be played (on top) and one for the domestic cartridge lockout donor (on the back). Unfortunately, it was created back when most of the games only used the middle section of the cartridge slot, so it doesn't have a wide enough slot for special chip games like Star Fox and Yoshi's Island.
I double-checked with my SNES Game Genie, it has a wide slot on the top, but the extra pins aren't connected to anything.. it has the middle section only on the card edge side.