I just got the 1.1 beta firmware for my BMCC and I thought I would shoot a quick test. This is shot at 300mm with IS off, the on. The audio is in camera and you can hear the IS motor running :) not surprising, don't be alarmed!
This was my 70-300mm f/4.5-5 lens @300mm Hand held.
my Tamron 17-50mm f/2.8 works great as well!