
The Apple Watch became available for pre-orders on Friday as well as for try-on appointments in Apple retail stores around the world.
One MacRumors reader, Louis, was able to slip off the bottom band during his Apple Watch try-on appointment to discover that the hidden diagnostic port on early models still remains in the retail versions.

Thanks Louis
Update: John Gruber notes that his review unit has the port, but it is covered up:
Article Link: Retail Apple Watches Still Have a Hidden Diagnostic Port [Updated]