Sparrow for iPhone may be considered abandonware at this point, but its developers did promise to update it for the iPhone 5's larger display, and today they did just that. The updated version of the email client now takes full advantage of the iPhone 5's extra pixels, allowing you to see more emails in your inbox and more of your messages at once.
In addition to the proper iPhone 5 support, Sparrow now has the ability to import passes received in emails to the Passbook app. Prior to this, you had to open passes through the iPhone's native Mail app in order to import them into Passbook. It's not clear if Sparrow will receive any more feature upgrades after this, but hopefully we'll soon see an official Gmail client for iOS using Sparrow's technology, seeing as Google purchased the company earlier this summer.