I guess that's actually not quite the right question. Of course it could, but anyone have any views on whether it could be done fairly easily and, if so, how?
The Pi will have a single DC power input so getting some sensing of instantaneous power being used shouldn't be difficult in principle. Then is there some way that GPIO inputs could be used (probably a little external circuitry being needed too, but keeping this as minimal as possible) to interface the sensing to the Pi? And finally a background task needs to be running that could eg log mean power consumption to a file every eg 5 or 10 or 60 minutes continuously for later analysis.
Why? Well I think that one of the most interesting applications for the Pi is going to be in off-grid computing applications. It's then really helpful when designing the PSU to have as good a fix on the actual power budget as possible and - if it were possible - it would be both neat and elegant to achieve this within the Pi itself