Google Updates Gmail App for iPhone, iPad and iPod touch
Google today announced an update to Gmail app for iPhone, iPad and iPod touch. Google added the ability to set a custom signature for your mobile messages and a vacation responder, both available through the gear icon at the top of the menu view.
Google also improved labels with support for nested labels (see below). Additionally, if you are using iOS 5, Google changed the notification sound so that it’s easier to distinguish when you've received an email.