I must admit that I also think power profiles would be a useful thing, has this been discussed before (e.g. on itt or on the maemo-developers list) as it would be useful to see some background if it already exists? If the power settings are handled by gconf (and most stuff is), then it should be possible to write an app to implement this sort of feature.

It would also be interesting to know if this sort of thing is planned for Fremantle/Harmattan/some future release.