Out of curiosity, why would they do this? It'd be more expensive (you think any deals they have with CC companies will carry through to a new and crowded market?) and they'd have a lot of competitors.
I'm not entirely sure what the rates are for GC/Paypal but I'm sure you could manage a merchant account that gives you as good of a deal and is optimized for the web.
For instance, how many people will buy through "Square" online when they are so familiar with PayPal.