There is a lot of debate going around after the sentencing of Bradley Birkenfeld, the key informant in the UBS investigation on offshore tax evasion. Some people say it is not fair that he got a stiffer sentence than bank executives because he was the whistleblower - sort of killing the messenger.
Other people are wondering if he really was a whistleblower - or only an informant, trying to reduce his sentence. Good recap of events on wikipedia here.
I think he might be considered a whistleblower, even if he did not give full disclosure to the investigators. He did try to ring the bell at UBS under their whisleblowing program in 2005. It is important to use strict definitions because there are some drifts in the language used by the press trying to make stories more sensational. For example calling the people who died in the World Trade Towers heroes - no they were victims - the only heroes were the firefighters and police who went into the towers to help. A hero is somebody who does an act of outstanding courage. Being in the wrong place at the wrong time does not qualify for hero status. So the same logic applies for whistleblowers. They need to make an act of moral courage to denouce the actions they object to. Just ratting on your firm once you have been nabbed does not qualify you for whistleblower status.