As an FYI, I got a pair of those and they've worked fine, but they give me somewhere between 2/3 and 3/4 of the number of shots I get from the genuine Oly batteries.
I'm just looking for a backup. I have yet to run out of power but for $20 I'd like to keep shooting if it ever comes to that.
(I wonder why OM batteries last so much longer?)
I got a pair of Maximal Power batteries off ebay for $17.89 and they work just fine in the Olympus charger. I can't tell the difference between the "genuine" and these as far as performance goes.