I would suggest to make SimpleXMLRPCServer.SimpleXMLRPCServer.register_function a decorator function.
See the attached file for the solution I wrote (l.209-240), which also works with the current syntax:
@server.register_function
@server.register_function('name')
@server.register_function(name='name')
or:
server.register_function(func)
server.register_function(func, name='name')
server.register_function(function=func, name='name')

So as far as I've tested it (py2.6), it is fully backwards compatible and supports decorators in addition.

Can you submit your patch as a unified diff -- it's not easy to tell where you made changes to that file. 
Can you also include tests showing how this is used, especially using register_function in both the old way and the new way you propose? Lib/test/test_xmlrpc.py is a good place to put your tests.

I'm not very used to working with bug/issue trackers, is there any tutorial here, where this is explained?

I did the stuff you asked me to do:

diff: http://paste.pocoo.org/compare/169357/169359/
test: http://paste.pocoo.org/show/169360/

http://www.python.org/dev/workflow/ and http://python.org/dev/faq/ should help you get started. The workflow doc will let you know what the process is around here. The FAQ will tell you how to setup Subversion, how to make a diff, etc.

With that said, I think your change could be useful. Being that it's a feature request, it will go into 2.7 if accepted.

OK, thank you for the links!

Do you still want me to do anything (like test cases etc.)?

Once you get a Subversion checkout of the source, have a look in Lib/test/test_xmlrpc.py for examples of how things are currently tested (using unittest). Once you get a feel for it, add new tests for what your changes do. The file you paste'd looks good as an example, you just have to make actual tests out of it now.

OK, will work on it and reply as soon as I have results!

I'm attaching a patch against 2.7 tip for an initial implementation of this decorator feature as well as sample usage in unittest, to get the ball rolling.

The modified function should work as a decorator while preserving backward compatibility to be used in a traditional method call.

Santoso - since this is a feature request it would need to be retargeted to 3.3

I see. Attaching a patch against 3.3 tip, then.

sorry, I totally forgot about this...