How were they calculating operating margins?

Lots of Apple bashers love screaming about how Apple has huge margins because the cult will buy any old iPoo, yada yada reality distortion field.

But on the Apple financials call they pretty consistently come in just under 30% on their product margins, and these guys (asymco) have them peaking at almost 50%.

Is this based on some backyard analyst's estimated component cost breakdown? In which case it is a worthless guesstimate, or is it based on official numbers?