Enabling XO features on other distributions
It is fairly straightforward to get Linux distributions to boot and run on the XO, since it is a "just" an X86 computer. The XO has several unique features that require additional steps to enable.
This work is present in the Fedora adaptation that is the normal operating system for OLPC OS images (presumably the changes are either in olpc-specific packages or modifications to Fedora packages, see a recent build log). This page documents the changes that other Linux distributions require.
Input controls
Controlling the backlight
When the backlight is off the video becomes effectively high-res monochrome (?).
See http://dev.laptop.org/~pgf/brightness.sh.txt
Gamepad keys
On a traditional PC keyboard, the keypad area to the right contains duplicate arrow, pgup/down and home/end keys that are operational when numlock is not in effect. The gamepad produces the same keycodes that those keypad keys do, thus the dpad produces keypad up/down/left/right, and the circle/cross/square/check keys produce the traditional keypad page up/down and home/end.
You could run a very simple daemon that eavesdrops on an /dev/input/eventNN node in order to support XO's multi-media keyboard keys. if there's not already a packaged way of doing it.
The slider function keys
Stylus pad
The extended stylus pad either side of the track pad. Note this feature may be removed from future hardware.
Lid sensors
These need to trigger screen off or enter e-book mode.
EC interface
The embedded controller can provide battery info and charge status. This may show up under the power interfaces, may not have stable API.
Backlight controls (see http://dev.laptop.org/~pgf/brightness.sh.txt ).
Mesh mode
XO uses special firmware to implement a early draft of 802.11s mesh networking (??)
Hardware encryption engine
Camera details
Mic input
kmix sees the sound device, including DC input mode, which I didn't expect, but I haven't sucessfully recorded anything yet)