Email attachments have been limited to files forever, but now Google is rolling out a feature in Gmail that lets you attach money. Using Google Wallet, a new button ($) in the Gmail compose window will allow you to easily send money as a gift or repayment. On the back end its the same as the money exchange system offered within Google Wallet, which means it's free if transfered from a bank account. The sender will have to pay a 2.9% fee per transaction (minimum $0.30) if using a credit or debit card. Money can be sent to people who don't have a Gmail or Wallet account, though the recipient will need to sign up for Wallet to accept money. Once someone receives money, they can deposit it to a bank account or use it anywhere Wallet is accepted. While Google has offered money transfers for some time, the update gives the feature prime real estate in Gmail — making it likely that it'll grab some business from competitors like PayPal. Google says the feature will be making its way into Gmail for users over 18 years old over the next few months.
Update: This post was updated to include information on transfers from bank accounts and transfers to users who don't have Wallet accounts.