According to the
always sometimes occasionally reliable FOSS patents, Apple made a conscious decision to allow Samsung to launch the Galaxy S III on time... so that the case could go to trial sooner. Apple had the option of filing a temporary restraining order to potentially stop the shipment of the SGSIII, but doing so would've been a risk for a few reasons.
Because Apple and Samsung are still in litigation over the Galaxy Nexus, Apple could attempt to stop shipment of the GSIII using a temporary restraining order (TRO). In order for the TRO to be granted, Apple would have to prove that there aren't enough technical differences between the two phones; consequently, by their logic, the GSIII should be tied up as well.