Barely in the hands of customers and already the iPad is being subjected to the weekday grind.

9to5Mac is reporting that the iPad has already been enlisted as a point of sale system in San Francisco at the Sightglass Coffee Shop -- complete with the custom iPad stand you see above, which swivels between customer and barista.

Sightglass is probably one of the first (but likely far from the last) to implement the iPad in their retail store, using the Square payment system developed by ex-Twitter exec Jack Dorsey. Square allows Sightglass customers to to swipe their credit card into the iPad (using the white block plugged into the headphone jack at the upper left corner) and sign the touchscreen, then the iPad gets swivelled back to the employee to complete the transaction.

It’s probably a given that we’ll see more uses of the iPad this way -- after all, $499 is a drop in the bucket compared to the cost of most POS systems. You can check out a video demo of the Square system on YouTube.

And if you happen to be in the San Francisco area, be sure to stop by Sightglass Coffee Shop and see the iPad in action… we hear their coffee is quite tasty, too!

(Image courtesy of 9to5Mac.com)