As far as I know you could always get a visa at the border during the Olympics if you had a HKID card. If you are an American passport holder then you never had the right even pre-Olympics with the HKID card (although I could be wrong, maybe the American issue is only for those without the HKID card, an American HK Resident can clear this up).
As an Australian passport holder with a similar visa and HKID card to yours I could pay $150HKD for a one time visa at Lo Wu for Shenzhen only (was always a Shenzhen only visa when you get at Lo Wu). I did not do this during the Olympics because $150 is a bit to pay when I can go shopping in Hong Kong, but I did go to Lo Wu and ask in person (the $150 is for Australian Passport holders who also have a HKID card, I can imagine other Passports vary in price).
According to ChinaVisa at HK this situation will change on the 17th of this month (you can get a multiple entry from their office, during the Olympics you could only get a single or double entry into Mainland). Their visa is for all of Mainland. You can phone their office with any questions on 2369 3188 (Forever Bright Trading Limited).