Google recently announced the ability to send and request for money through Gmail app. This feature is currently available for US. However, the global release of this feature is expected to be in the near future. Previously this feature was only available on the web platform and now Google has implemented this feature in the Gmail Android app.
This feature works with Google Wallet and a user can tap on the Attachment button on the Gmail app to send money through Google Wallet. Google says this method of money transfer is really easy and secured. Users can also refill their Google Wallet by using credit/debit card.
Source: Google official blog