Since there are now a few NEX-5 KAPers, I wanted to report that I ordered an extra battery for my NEX-5 for $12.79 from this Ebay seller
The battery charged normally in the Sony charger and is working perfectly in the camera.
While I'm at it, I'll also report that I have successfully (and happily) used a gent360-LED
to trigger the NEX-5 via infrared pulse.
My latest test flight yielded this 2-image stitch taken with the 16mm lens at f/5.6 and ISO 400: