Via an e-mail from Kate the Hoosier Librarian:
I just signed up for PayPal Mobile, so then I was thinking, what is this good for?
Here’s an idea: Your library has a PayPal account, a patron needs to check out materials, but has something he needs to pay. He doesn’t have enough cash on him, you don’t take credit/debit cards, and he doesn’t have his check book. He whips out his phone, PayPals you the money via text message, you instantly receive a confirmation email, the fine is paid, he gets his stuff and goes away happy. How awesome would that be?