Just like Adam Curry I'm trying to get the xmlStorageSystem running on Frontier. It's not working perfectly yet, but this way I at least get to learn more about Frontier. To be able to do some more testing, I created an xmlStorageSystem interface. If you've got Radio Userland, and upstreaming enabled, then try it with your username and password.
To be able to try some XML-RPC calls, I built a simple interface around the XML-RPC client, so that there is now an online XML-RPC debugger. Then I found out that Graham Dumpleton had one available already, including introspection.