I hope that Samsung stopped the phone identifying non oem batteries and refusing to charge them in phone like they did with the Moment. That was an annoying "feature".
Samsung still has that in place, at least for Vibrant and Epic.
Message with phone off and oem charger hooked up: alternating charging symbol with battey symbol with yellow trangle warning. no charging occurs
With phone on, message: "Info: Battery is not connected". no charging occurs.
Right now I have two ebay batteries doing that and two working ok (albeit testing to 1200 mah
The batteries that are displaying the flashing warning will charge in the external chrager but not in the phone.
And ironically the bad batteries are the outright claimed "OEM" with counterfeit G7 with fully faked Samsung labels and part nuimber.
The other ones, the working 1200 mah ones, have labels that look like samsung labels using samsungs font and logo, but say "For Samsung" with the "For " in tiny print. It is illegal to use the Samsung font since that constitutes a logo use without permission, and it does make their sale fraudulent as well, but they are trying to slip by with that little "for".
I have had a lot of success with ebay batteries in the past, but there is a LOT of garbage out there in terms of Galaxy S knock off batteries right now.