I applaud people in the BTC community for developing more advanced financial instruments, but implementing them like this is so 1994. There's no way this is scalable. Every order is hand processed via email. Maybe I'm just spoiled, but check out the order fulfillment instructions you get after clicking through for a purchase:

In order to buy 1 PUT @26.5 contracts expiring month after next at 27.74233656 each please send exactly:
3.18764653BTC

at the address
1JPvucRfu3ZzEvfBUQTJwsxMrZjeTqD6zR

You must send an email to office-at-polimedia.us BEFORE sending bitcoins, containing the amount quoted above and the bitcoin address you are seding from. Optionally you can also include the address you want proceeds forwarded to. If you do not do this it may not be possible to prove ownership later on!

READ CAREFULLY! to understand how this works :

- The amount you actually owe has been rounded up at the 5th decimal place. The last three decimal places are used to signal the order, as follows : the sixth carries the option type and maturity (calls this month 1, next 2, after next 3 then puts 4, 5 and 6) ; the seventh and eigth carry the strike. [Is that a hack or is that a hack? I have a visceral distaste for loss of precision, even where it may not be obviously needed.]

- The amount itself encodes the quantity bought. You will be credited as many whole contracts as can be purchased by your order at the time of processing. I will do my best to process imediately, but due to the somewhat imprecise timing of the bitcoin transactions (by block rather than by timestamp) there may appear slight delays. [manual order processing?]

- Once your transaction has been accepted and processed, you will receive change, for the fraction of contract that could not be bought, as well as for the sums added as explained above for clerical reasons. The sending of this change is the confirmation of your purchase. In general a confirmation should show up within the hour. However, since I am currently handchecking all transactions to make sure things run smoothly, this may be delayed. Even in case of delay, you can rest assured that your order will be processed only with quotes valid for your block.

- Options will not be quoted on the last day of their month (so no quotes after the last minute of the last Thursday of each month for options expiring that month). This means the last you can sell any options is late night Thursday. Times are the same as bitcoincharts use, so make sure you account for that.

- All options positions not closed by the first minute of last Friday in their last month will be automatically exercised, at the weighted average price of the day as published by bitcoincharts. This means that options out of the money will be discarded. Options in the money will have their value converted to BTC at the conversion rate then current. The amount of BTC thus obtained will be sent before the following Monday (so until the last minute of Sunday) to the address that originally bought the contract. The reason to do it this way is that I do not think the market is liquid enough for spot prices to be fair, and since I'm using Friday average price I can't trade on Friday.

- I reserve the right to refuse any transactions for any reason (including excess risk load on the book, order too large to effectively hedge etc) or for no reason whatsoever. All refused transactions will be refunded within 48 hours.

- You are not required to use this page, if you'd rather hack the orders directly by the recipe explained above that's fine. However be aware that uninterpretable orders will be treated as donations. You will not get a refund. VERY IMPORTANT : bitcoin before v0.3.21-beta rounds automatically to 0.01. DO NOT USE IT OR YOU WILL LOSE YOUR MONEY. Bitcoin v 0.3.24-beta correctly sends all 8 decimals.

- Please keep all orders over 0.1 BTC. If you send less than that it will be simply treated as a donation. You will not get a refund. This only applies to BTC you actually send to open new contracts - cases where you are ordering the sale or beneficial exercise of contracts you already own are specifically excluded. This arrangement is needed to protect from transaction spam and also allow signalling of sale/exercise orders.

- If for whatever reason there no longer exists a reliable way to calculate average prices I will stop quoting. Options whose execution is impeded by this event will be refunded at price originally paid. In principle something like MtGox going offline again would be in this class. Hopefully that will not happen again. If the bitcoincharts aggregator goes offline I will either pull the averages from someone else or write a script to do the averaging.

- This is a service for responsible adults. While it is offered and operated by me, Mircea Popescu (otc, twitter), I specifically disclaim any liability for anything whatsoever. Whatever determinations or inferences as to credibility or counterparty risk you make or may make are entirely your responsibility. This service is offered, as all software is offered, with no guarantees whatsoever, not even of merchantability, fitness for a specific purpose and so forth.

The system is designed to allow anonymous use of the exchange. As such, it is impossible for me to take on any counterparty risk whatsoever. For that reason it is also impossible for me to otc-rate anyone based on their transactions with the exchange. The situation is not symetrical, however, seeing how anyone dealing with the exchange is taking on my counterparty risk, and as such is in a position to rate me. I appreciate it if you do.
Special thanks go out to random_cat and ezl, who have offered invaluable advice during the early stages of this project.