I think if they gave you the option in the Mail app to attach things to emails it would be more obvious to people what the limitations of the phone are, i.e. the only thing you can email is a photo.
If there was a 'Attach' button in there people would probably expect to be able to attach whatever they wanted, like documents when the document editor apps get released, which of course they could not do.
I know that the email solution is much touted over the lack of MMS support, but MMS would be a much better solution for you sending your pictures. Not only would it allow you to send more than one at a time (if the iPhone is indeed limited to that), but also the mail app reduces the quality of the pics when you attach them. You can MMS at a higher resolution than the iPhone allows you to email pics at.
