Nice. This must be a fairly new feature, since 360 pads didn't work with
Trisquel the last time I checked.
I've added some information on how the axes and buttons are mapped here,
along with information about the PlayStation 3 SIXAXIS pad.
It seems that the inputs mappings are different to those used by the official
Windows driver, but that's no bad thing - the Microsoft driver combines both
triggers into a single axis, and doesn't allow the central logo button to be
used.
The information was compiled using a simple SDL test program, in case anyone
was wondering.