Could you suggest well-written books on RMI, especially in terms of suitability for preparing for SCJD? Does anyone have experience with William Grosso's Java RMI (2002)? Is it good? Is it appropriate to use now - has RMI changed much since then?
What you get from any decent Java networking book should be enough.
No, not much has changed, (certainly at the core, and you don't need much more) except that you no longer will have a skeleton class. The current rmic no longer generates it as it's no longer needed by the current JVMs.
Remember that you're (at least in my assignment) aren't allowed to use any of the advanced stuff related to different line protocols, security, etc.