What would be really nice is that shareholders get some kind of priority to order and get delivered a miner board when the production starts ...
my 0.02BTC
Yes - ASICminer will have to solve the allocation problem.
While FIFO (first come, first serve) is usually the simplest it may not be the best strategy (BFL has similar issues and they employ some lottery scheme).
I suggested a dedicated GLBSE account for that purpose a while ago. Each share would reserve a certain allocation for a particular series of chips. Then you have a market for ASIC hardware orders. ASICminer could provide an initial incentive to count the IPO price of the order towards the final hardware price. The only problem with that scheme is that you get speculators, which just buy these orders in order to sell them at a higher price. And these speculators may not be interested in buying the actual hardware, which may delay the selling and inflate the price of the hardware. To counter that, the shares would have to be issued at a significant fraction of the final price, e.g. 50%. Then the speculators have a significant stake and need to get their investment back ASAP. Also another issue is AFAIK that GLBSE charges transfer fees proportional to the traded asset. This would cut into the profit from sales.
In the end, ASICminer has to find a way of filling the orders with either an optimal strategy to make profit, and/or one which has the least damaging effect on reputation and sales.