In what sense do you mean "saving" the chart? You could call the getChartWrapper() method, serialize it to a JSON string, and then save it in a session variable or cookie. You can't save the chart as an image or anything like that, though.
You could also, conceivably, save the contents of the iframe, though I believe you would lose the interactive features of the chart in doing so. jQuery can get the contents of the iframe using something like this: $('#my_chart_div').find('iframe').contents();