Sorry, I think part of my post was cut off after a botched c&p.
I have a GS-580P (great bike computer) and in the winter months when I spin on my trainer, having a power reading would be nice data point. Kurt Kinetic trainers are calibrated from the factory, so the power readings can be based on the equations I posted previously. KK sells a power meter specifically for these trainers for around $70, but the two issues I have with it are:
1. It runs off of a separate wired speed and cadence sensor (really on the speed sensor is needed).
2. The power reading will not be synchronized with the rest of my GS-580P data.
Adding this function in a training mode will: eliminate the need to buy a separate power monitoring device, not require having to mount another speed (and cadence) sensor, and will give me accurate power reading that is synchronized to my other data (i.e. hrm, cadence, speed)