Ask Slashdot: An Open Handheld Terminal For Retail Stores?
Evil Al writes "From the ubiquitous Verifone card terminals to the fancy Apple Store terminals, point-of-sale devices are everywhere. But does anyone know of an open terminal (with printer + Wi-Fi), preferably running Linux, that we can use to run a custom application for retail, made by a reputable manufacturer?"
If you intend to process credit card payments through your custom application on the point-of-sale device, you'll likely fall under the purview of the Payment Card Industry's Payment Application Data Security Standard (PCI PA-DSS), which may require a source code audit and limit what you can have the software do. That may be no problem for you depending on your resources and intended use of your software, but it's worth keeping in mind.