I thought this was old news and everyone was already using these. Apparently after posting my aftermarket battery video for the 550D & T2i, I received many questions on the 5DM2 / 7D aftermarket batteries.
So these batteries work differently. They don't charge on OEM canon chargers, and they don't display battery life. Other than that they are dirt cheap and work just as long (i think so). I'm also using aftermarket China 'battery grips' on both my 5D Mark II & 7D.
More information about where I bought them at cheesycam.com/canon-5d-mark-ii-7d-cheap-china-batteries/