OOFy
Please Note: OOFy is not currently in active development.
OOFy is a tool originally designed for the first generation iPhone. It allows you to set your "Out of Factility" or "Out of Office" message for Microsoft Exchange 2003, 2007 and 2010 mailboxes. This application is not currently under active development due to difficulty supporting different people's firewall configurations. This application works the same on all generations of the iPhone.