The emacs remappings are related to this:
http://bitbucket.org/tavisrudd/emacs.d/src/tip/dss-keybindings.el
(also see http://xahlee.org/emacs/keyboard_shortcuts.html)

Here's the OS X app I'm using:
http://www.orderedbytes.com/controllermate/
It's awesome, despite using a weird visual programming language for the rule definitions.  'AutoHotKey' seems to be the Windows equivalent, though I don't think it allows you to define separate rulesets per usb device.

I haven't found anything exactly like it for Linux, but these might work:
- http://usbhotkey.sourceforge.net/
- http://code.google.com/p/autokey/
 (seems hard to install without a debian based system)
- http://www.autohotkey.com/forum/topic54494.html
- or AwesomeWM's own keybinding system

To get something equivalent to my controllermate setup you would need:

- the ability to remap a single key into a multiple-key output sequence
(I know the Kinesis can do this at the hardware level, but I don't trust its potentially volatile memory and hate the opaque interface for defining them)

- the ability to activate sub-maps like I'm doing with my thumb-modes.

- the ability define separate maps per usb input device.  Hopefully usbhotkey can do that.

Here's some other related notes:
http://debian-user.blogspot.com/2009/01/autohotkey-for-linux.html
http://www.hotsolder.com/2008/08/autohotkey-for-linux-sort-of.html