When markets move lots of money is lost or made through the use of deriviatives. It does not surprise me that a number of large banks don't have a proper real time control on their derivatives situation. Technically this is actually more difficult than most banks are capable of.
I would be interested in finding out a bit more about Soc Gen's losses, but it strikes me that they simply don't have automatic reconciliation. That allows people to conceal losses by putting false entries into the system.
Automatic reconcilation has been available for many years, but still a lot of financial organisations don't have this sort of system. Soc Gen sounds like one of them.