Interesting concept, wk. I'm a bit confused how the "sell-a-share" thing would work in practice. If I read your description correctly, if I wish to sell shares, I must have already mined those shares. I'm not selling based on my hashing power, but rather what I've already hashed and recorded in your share log.
Is there a limit on when those shares can be sold? For example, a share that is about to drop out of the 8N window is certainly worth less to a potential buyer than a share that has just been added. I, as the seller, have potentially already been paid N times for an old share.
Using your hypothetical example of 1000 shares worth 1BTC, isn't that 1BTC over the lifetime of those shares? Some of that 1BTC has already been paid to me as the miner prior to my sale. How is a buyer supposed to know the age of the shares being sold, and whether or not the value proposition is there to engage in the transaction with the seller?
As noted in my writeup:
Shares near the extreme end of the share log (soon to be discarded) will not be able to be sold. Generally newer shares will have more value than older shares as they have the highest chance of being awarded by blocks as many times as possible. The market will have some generic probability calculations available for sellers to use in pricing.
While shares are for sale but unsold/not reassigned the miner is awarded for the shares as per normal.
So in short, yes the example I used was simplified. The 1 BTC in the example is the expected value over the life of the share.
Miners will be able to set their market accounts to automatically place shares you mine for sale at a calculated price immediately, or once they reach a specified position in the share log. When a buyer goes to buy a chunk of shares they will have plenty of information available to them, including the position of the shares in the share log, how much reward these shares have already earned, estimated remaining earnings of the shares assuming 100% PPS average, etc. Essentially, the shares can be sold in chunks that are in particular areas of the share log and the price set accordingly. Since the potential expected remaining value of any particular group of shares will be constantly changing, the sale pricing will always be based on an algorithm and not a static price set by the seller. The seller can choose the variables for that algorithm, however, when placing their sell order.
There will be some common sense limitations placed on the market. Since this is a buyer/seller facilitation that uses the block chain (ie, the funds for the sale never go through Eligius and instead directly to the seller), minimum sell amounts will be used to prevent spam. A seller can also set a minimum amount for a single purchase. This will, unfortunately, make it so the smallest miners can't really participate in the share market as it is currently designed. In the future I plan on adding a portion of the market for buyers to buy shares from smaller miners in aggregate by depositing funds into an escrow account. But, for the time being, however, buyers can only purchase shares though direct payments to the miner who is selling the shares.
Also keep in mind that this is a pretty new concept and it will evolve as things progress.
