The iPhone 4S seems to be in significant demand even weeks after its initial launch, with Barrons reporting that Best Buy stores are already selling out of the unites, with many such stores offering pre-orders or reservation lists to keep up with demand.
From the report:
[The iPhone 4S was] “sold out at the vast majority of stores that we checked with, with many stores notifying customers of device shortages in their automatic greetings.” Stores are taking pre-orders for the phone or creating reservation lists.
Despite the fact actual supply levels at the retailer aren’t known, and available stock from Apple and other retailers also remains a mystery, the report calls stok-outs at Best Buy a “litmus test” for US sales performance of the iPhone 4S in general.