That's one of the main purposes of serialization, to have the freedom to transfer JVM objects to other machines and invoke remote methods on them.
Precisely how's it done depends on which transportation mechanism you use as well as well as the software, although its usually some form of XML I believe. For example,
EJB and Web Services both use a form of serialization to transfer objects via RMI. Some web servers will detect whether or not external calls or truly external or not, and skip deserialization/deserilization of local objects as a performance enhancement.
[ November 04, 2005: Message edited by: Scott Selikoff ]