I have a suggestion, Why not define Runlevel 3&5 as Powersaving mode console/powersaving mode graphics and put some laptop specific services in those runlevels. As I have done now I run mobile_update, hdparm, toshset, apmd, apm-sleep, noflushd in those runlevels, and kill other services like pcmcia, network deamons, and then I will set it up so that linux will aoutomaticly change runlevel whn i pull the AC-Cord.