They don't have anything listed on their website yet for BlackBerry, just the iOS and Android apps.
I would think BB (and WM7) would be logical additions. It just might take a little time for them to port it over.
If you have a regular merchant account, some of the companies have a Bluetooth card reader. There are several apps available for processing credit cards. Most either connect directly with that company's setup, use a gateway like Authorize.net, or link to PayPal Pro.
Yeh this sucks! I have the card reader and have yet to find a Square android app that I can load that actually works on my BB Z10. If anyone can provide a link to download an Square android app that works I would really appreciate it. Thanks!