Bedework is an open-source enterprise calendar system that supports public, personal, and group calendaring. It is designed to conform to current calendaring standards with a goal of attaining strong interoperability between other calendaring systems and clients. Bedework is built with an emphasis on higher education, though it can be (and is) used by many commercial enterprises.
They won't exclude Java in the way that they excluded Flash on the iPhone.
Seems like there is no (official) JVM for the iPhone anyway...
Help me, I'm a prisoner in a Fortune cookie file!