Cool, I did not know about that service.
However, when I submit my parameters I get back "java.lang.IllegalArgumentException: Invalid or unsupported wkid: 54003".
My input point is WGS84 (wkid 4326), I called both setProcessSR on the GeoProcessor and setSpatialReference on the input GPFeatureRecordSetLayer to set those spatial references as well, but it looks like at some point it's still trying to go to the default SR of 54003 which Runtime I guess does not currently support?
EDIT: Fixed it, I wasn't setting the outSR on the GeoProcessor to WGS84.