Google has released version 2.3 of Gmail for IOS with new notification options that allow you choose to get notified for all your messages, only important messages, or none at all, on a per account basis. You can customise these settings from the in-app settings page. The biggest feature however is the new inbox which if you've enabled makes your mail group into categories so that you can see what's new in specific areas. Primary email is shown first and you can easily access access email in other categories by opening the menu. You can configure this feature by going to Gmail.com on a computer and hitting the spanner on the right of your Inbox.