I'm considering options for an isolated power supply (1mA @3V) with very low noise pickup and capacitance to mains/ground. Is there a simple optically-isolated solution, preferably using an off-the-shelf IC?

I see no theoretical reason why properly coupled LED + photo-voltaic generator (ideally, integrated into an IC/package) would not do the job. I would be satisfied with 5-10% efficiency (but do not know to achieve that).