When plugging the Madcatz XBox 360 wired controller into my computer,
it moves the cursor on the screen and makes my X desktop environments
unusable until the controller is unplugged.  The mouse cursor will go
left, and warp through workspaces.  Moving the controls on the gamepad
will change the behavior somewhat.  It doesn't seem to care what
desktop environment it's in.
With the joystick input module not installed, this doesn't happen.

By lsusb:
Bus 001 Device 006: ID 0738:4716 Mad Catz, Inc.

The above is what the joystick X driver is supposed to do.  If you don't
want that, you should remove this package...

Cheers,
Julien

Thanks, that explains a lot.

It's still a rough edge which needs work.  This package is installed
by default, so it could bother anybody:
xorg/xserver-xorg/xserver-xorg-input-all/xserver-xorg-input-joystick
... so a new user plugging a joystick or controller into a computer is
a recipe for a lost user.  What do we do about it?
We could disable this module by default, and have it pop up the
manpage in a terminal window if a joystick is plugged in while X is
running.

Whatever we do, we don't want X to automatically initialize a joystick
as a pointing device and start workspace warping with no explanation
given, because that's... just messy.

We could write a better description for the package while we're here:
"This packages provides the driver for joysticks and gamepads as
pointing devices on an X11 desktop." [...]

Depends: xserver-xorg-input-evdev, xserver-xorg-input-vmmouse, xserver-xorg-input-synaptics
Recommends: xserver-xorg-input-wacom
I'll gladly apply patches to improve the description.

Cheers,
Julien