You'd be crazy to be an early adopter of this product.
The founder of 'square' (and co-founder of Twitter) Jack Dorsey,
is working on something similar, and it will be better since he's already in this business.
If you're going to try this, at a minimum you should call your CC company and ask them what liability you have when you voluntarily hand over your card information to a 3rd party non-merchant for processing.