Corey mentioned it on Twitter a few weeks back:

@alexkingorg it’s the whole concept of new vs unread. I knew to open mail for new mail. Unread is a meaningless number.

BlackBerry, Android and Palm all have a notification system that allows the user to know when new email has arrived. The notification remains present until you launch the mail app.

On iOS, there is a “meaningless number” tacked on to the mail icon. Why couldn’t this be replaced (or augmented) by a “new” indicator that would get cleared next time you launched the mail app?

For example, if the unread count badge is red it could indicate the arrival of new emails since you last looked at Mail. It’s your key to go take action.

Once you switch to Mail after the arrival of new mail (red icon), the icon would revert to grey.

Simple, meaningful, useful.

And while we’re at it, some sort of LED indicator light on the device would be great so that you know you should take a look to see what needs your attention. I don’t want my phone vibrating several hundred times a day with the arrival of each new email, but I would like to have it tip me off when there is something that I should look at.