Apple has updated their Apple Store app for the iOS devices that let you check out prices, buy products and track your purchases on the go. The update brings support for Apple Store gift cards with Passbook support and Siri integration.
Now you can purchase Apple Store gift cards for your friends and family through the Apple Store app. When you send a gift card, it arrives as a mail to your recipient. They can then choose to send it to their iPhone and it appears in Passbook through iCloud integration. They can then just walk into an Apple Store and purchase items by showing the pass in the Passbook app.
Another cool new feature is integration with Siri, so you can now just ask Siri for prices of Apple products and it will provide them if you have the Apple Store app installed.
Both features are only available in the US for now.