I’ve noticed another difference that amounts to an annoyance for me between how a Windows Mobile device behaves and how the iPhone handles the same thing – it just doesn’t.
If I use a Windows Mobile device to reply to or forward an e-mail on my Exchange account, when I fire up Outlook on my PC, it will properly reflect the status of that e-mail with the appropriate icon and information banner near the header.
The iPhone is apparently unable to inform Exchange of a change in status beyond the fact that the original message has been read. The Outlook icon for the message just changes to the open envelope without any of the proper arrows to indicate if the message was replied to or forwarded.
It seems to me that this shouldn’t have been too difficult to implement, but is just another example of why I find it hard to recommend the iPhone to corporate users in an Exchange environment.