The iPhone as I see it is not really aimed at people who need the Blackberry style rapid email. For one thing, if you actually want to hear your email arrive with the iPhone you'd pretty much need the thing taped to the side of your head, the alert sound is so quiet.
For my job the iPhone is pretty inadequate for this reason, I rely on the ability to be paged through SMS 24 hours a day. The alert sound on the iPhone is not loud enough to wake me up, or even hear it in anything other than a quiet room. Since getting an iPhone I've had to go back to carrying a pager and can't rely on SMS any more.
I agree..and not a bad idea! I might have to try some tape.