I'd imagine not seeing as there is probably proprietary code within but if it runs on Android, why not Maemo?

https://squareup.com/

SquareUp has announced they will be releasing a "secure" version of their application, so it's highly unlikely they'll be publishing any details, in an attempt at security through obscurity.

MagRead can display data off a Square reader just fine, then do what you will with the data :P