Use button to reset bifferboard
On the bifferboard cases the GPIO button is labelled as "Reset" - so I've worked out how to really make it work as a reset button :-)
(There might be a "better" way to do this, but this is quick-n-easy)
Note that this is a software reset i.e. if Linux crashes, you'll still need to reset "the hard way" by unplugging the power connector, however doing a software reset means that Linux gets shutdown 'properly' (i.e. disks unmounted, etc.)
Edit the file /etc/rc.d/S95done (this seems to be the openwrt equivalent of rc.local?) and just before the last } add: gpio-resetbutton &
You need to manually start it the first time (by typing gpio-resetbutton & ), after that it'll get run at every startup by the previous step.
When you press the button, gpio-resetbutton will now call the reboot command (you can watch it rebooting in the serial console, if it's attached).
To stop this happening, you just need to take the line out of /etc/rc.d/S95done to prevent gpio-resetbutton being run at startup.
I'll hopefully get this added to SVN soon, but until then you can get the source here http://users.durge.org/~lurch/bifferboard/gpio-resetbutton.c