LÖVE

I've tried looking it up, but I haven't found any file that gets my gamepads to rumble. I know they work, bioshock shakes them thoroughly, and I get true for isVibrationSupported. I'm currently working on a macbook air if that info offers anything.

Is this a bug or am I just missing something?

What gamepad and driver are you using?

Xbox360 with tattiebogle and PS3 with bluetooth

For the 360 controller make sure you're using this version of the Tattiebogle driver. The versions on the tattiebogle website have horribly broken rumble support, unfortunately.
As far as I know the built-in driver for the PS3 controller in OS X doesn't have rumble support at all.

IT'S ALIIIIIIIIIVVVVVVEEEEEE!!!!!!
for the 360 controller at least

Thanks so much!! I was replaying bioshock and was just blown away by how atmospheric as simple an input as rumble was.