Square opened up its Square Cash service to the public today, after spending several months in beta. The service allows users in the United States to send money to one another using nothing but an email address and a debit card.
The service is easy to use. Transactions are free, and there's no need to setup an account to process them. Money can be exchanged by sending an email with a dollar amount in the subject line and cash@square.com in the CC field...