PMON 2000 is a firmware that was orginally developed by swedish company called Opsycon, but the copyright also mention Rtmx Inc and ipUnplugged AB. The code is licensed under a four-clause BSD licence.
More info is available at http://www.pmon2000.com. Regretfully the website has not been updated for some time as develoment of the PMON2000/SDK have taken up all time.
Source should be available from anoncvs.pmon2000.com.
This firmware was used at least in evaluation boards from Momentum, like the Jaguar ATX.