This was confirmed by Tim Cook last month and was followed by a report in June that claimed that we could expect them in two weeks. Well according to the folks at BGR, it looks like the watches could already be in the stores. They have heard from their sources that shipments of the Apple Watch have already arrived in Apple Stores around the country.
However they note that the devices are only available via in-store reservations or for personal pickup when purchasing online or through the Apple Store app. This seems to suggest that walking into an Apple Store and buying a watch might not be possible just yet, but presumably with the shipments coming in, hopefully it won’t be too long before they will be open for sale to anyone who comes in.
In any case Apple has yet to confirm the watch’s in-store availability yet so do take it with a grain of salt for now, and perhaps if purchasing the device in-store is something you want to do, maybe calling ahead to double check with your local Apple Store might be a good idea.