What is required to fly over Cuba enroute to another country? I understand that you need to get an overflight permit before entering Cuban airspace, even if you aren't landing there.  How do you go about getting permission to overfly them enroute to another country?

Updated now that flights to Cuba are allowed by US operators.  What has changed, and what are the requirements now?  Can we pay them directly yet?
The IACC navigation fees are approximately $170 for a small jet, plus there is a service fee to issue. There is a full list at World Air Operations and you can in fact order the permit for Cuba online there too.