Gmail for Android updated today to let users respond to e-mails directly from push notifications.
That's not all: the update also allows archiving and searching Gmail from the notifications window.
The company suggests tweaking your settings to limit the amount of push notifications you get for e-mails:
"You can combine this with existing notification features like the ability to customize which messages you receive notifications for and set up different sounds for individual labels. So if you filter and label all the messages from your mom, you could set a ringtone to let you know you received a new mail from her and then quickly reply (because we know what can happen when you ignore your mother!)."