Actually, the sidewall lights, if luminated to full intensity, along with any ambient sunlight and light from the overhead bin lights (partial obstructed by the overhead bin doors, of course) provide sufficient light to charge the photoluminescent strips. It is simply not feasible to keep the overhead bin doors closed during passenger boarding.
I respectfully stand corrected. As such, I cannot claim to know what AirTran techops divisions plans on this front in the future. An "updating" to the photoluminescent strips would seem to be a possibility.
[Edited 2005-01-18 23:28:54]
Ignorantia juris neminem excusat.