Google's not launching its own currency (not yet, anyway), but it does plan to soon let people send each other money as easily as sending an email.

In fact, it's going to let people send each other money by sending emails. Over coming months, Google's Gmail users will find a "$" icon added to their email attachment options. When they click the symbol they can specify how much money they want to send to whom.

The service will at first be available in the US only, to users 18 years of age and older. Recipients do not have to have a Gmail account or Google Wallet.

For users whose bank accounts are linked to Google Wallet or who have an existing balance in their Google Wallet account, sending money will be fee-free, Google Wallet product manager Travis Green wrote in a blog post on Wednesday. Transactions involving credit or debit cards will incur a flat fee of 2.9 percent (with a $0.30 minimum).

"Paying back your friends is now as simple as sending an email, whether you’re chipping in for lunch or reimbursing your roommate for your share of the rent," Green wrote.

Sending money in Gmail will be possible only from desktops, although mobile users can transfer funds using Google Wallet.

By the way, while the service hasn't rolled out yet, if you have a friend who's a Google insider, you could get earlier access if he or she uses the service to send you money.