Peter Faris QC has an excellent analysis of the Schapelle Corby case. Nobody other than Schapelle really knows if she was guilty. If not guilty she is extremely unlucky. Its possible that the chain of events claimed by her defence team occurred (see point 45 in Peter’s post) but I tend to believe that the less complex answer, she did know, is more likely.
One thing that has struck me as odd through the whole case is that the drugs were in a boogy-board cover with, according to most reports, little other than a board in it. How can you not notice an additional 4kg package?