According to GWcheck it is:
Novell is committed to providing a solution that allows users access to their email, calendar and contacts on the iPhone. As the SDK was just released, we are still working out the details and will announce more specific plans when appropriate.
There has been speculation from other sources about Lotus Notes working on the iPhone as well.
There are still plenty of organizations out there that do not use Microsoft Exchange. Those that don't, typically use RIM's BlackBerry Enterprise Server solution. It will be nice to see either RIM jump on board the iPhone bandwagon (I don't see that happening) or companies like Novell working with other visionaries to bring their services to Apple's iPhone.