Ok, I apologize for being to hasty. Below you can find my answers:

1. SlowParser used in xmlrpclib doesn't deal with namespaces in any reasonable way. If there's a namespace prefix for tag, it's not separated from tag name, but passed as part of tag name. But I agree - this should be done better.

2. Well, I suppose that content of http://ws.apache.org/xmlrpc/extensions.html will only convince you that this patch is just for Java library and you reject it. I didn't find support for <nil/> in Perl nor Ruby. One of PHP libraries also support <nil/> (and <ex:nil/>) - http://phpxmlrpc.sourceforge.net/, but AFAIK it doesn't require/provide any namespace at all. It just treats ex:nil as a synonym for nil, probably to be compatible with Apache library.

All in all - I think that my patch should be rejected. I can send simpler patch that would work like phpxmlrpc does - just accept ex:nil as well as nil and not try to analyze namespaces at all.