It looks like Apple will run out of iMacs this month, and it won't be able to replenish supplies until September. That's three full months without a mid-range desktop computer to sell.
(This reminds me of one of the main problems with the Communist system -- someone in the Central Command orders too many shoes and not enough shoe laces. And the following year, there would be too many shoe laces and not enough shoes. It's very, very difficult to get it right.)
Allow me to say, this could never happen in the PC world. If Dell runs out of desktops, I just call Gateway instead who would be happy to serve me. If Gateway is out, I would call the independent computer maker down the street from me. As a last resort, I could buy the parts and make it myself. The hardware sources are endless -- there are literally thousands of PC makers.