Discover has updated its mobile app with a new feature that might be a sign of things to come in the world of Passbook.

On top of the normal balance check and account summary functionality available on every card brand's app, Discoverdddx lets users redeem Cashback rewards for gift cards and eCertificates on its app. (As the name implies, Cashback is Discover's reward program for using its card to make purchases.) Additionally, Discover adds an "Add to Passbook" feature to those eCertificates and gift cards. In effect, Discover is making its Passbook integration into a more wallet-like mobile wallet experience instead of just a storage space for coupons and boarding passes.

American Express added a similar feature allowing app users to pay for purchases using its Membership Rewards points, but that option is only available to users after a cardholder uses her plastic card. The Discover app takes it one step further (and closer to what Starbucks does with its Passbook integration) by storing a live gift card in Passbook.

Though not new with the latest update, Discover's app also includes its Money Messenger feature. Money Messenger is Discover's peer-to-peer payment service powered by PayPal. The service lets Discover cardholders send money from their mobile phone to any mobile number or email address. The recipient then logs into a PayPal account (or signs up for one) to access the funds.

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