GMail now allows you to send money
gmailblog.blogspot.com
gmailblog.blogspot.com
>We’re rolling out this feature over the coming months to all U.S. Gmail users over 18 years old, so keep an eye out for the $ icon in the attachment options.
I don't have the dollar icon when I compose in Gmail, but I haven't used Google Wallet before.
I think the name actually might be a problem; it's really hard for me to explain to people that I want to pay them in "square cash".