VC VR OS IS experience???

[Hägar the horrible]

Hi folks,
the last couple of months a bunch of new lenses with vibration controll/stabilizer or whatever it is called hit the market.
So far I havent found a lot of information about the efficiency of these systems. Is there any data around which compares Nikon, Tamron, Sigma, Canon technologies? Are there differences by focal lenght or by brand or is it a question of individual implementation?